NOVA

NARRATOR

In the heart of Lithuania, archaeologists search for a tunnel rumored to have been dug by desperate Jewish prisoners inside a little-known Nazi execution site called Ponar. (gunshot)

RICHARD FREUND

They were systematically exterminating people at this site.

ABE GOL

Once you get taken away, you'd go to Ponar to die. Nobody comes out of Ponar alive.

MAN

Let's look at the IP, see what we get.

NARRATOR

The investigation will open a nearly forgotten chapter of the Holocaust-- the story of Vilna, a renowned center of Jewish culture, destroyed by the Nazis. Now, a team of scientists from around the world has come here...

PAUL BAUMAN

Could be a trench, could be a pit.

NARRATOR

...searching for the last traces of a vanished people. Where's the grave here? Who were they?

AVINOAM PATT

Vilna was one of the most important cities in Jewish history.

FREUND

It had the greatest scholars, it had the greatest writers.

NARRATOR

Armed with advanced scientific tools, their work will help restore the memory of this lost world. and something more.

ALASTAIR McCLYMONT

We're picking up two hotspots.

NARRATOR

A story of hope in the city's final hours. But time is running out. Few remain who remember. Is there anything left to be found?

FREUND

There is something there.

NARRATOR

The secret history of Vilna, and the legendary Holocaust escape tunnel. Take the moment, take the moment. Right now on NOVA. Major funding for NOVA is provided by the following... Just six miles outside of Lithuania's capital city is a forest park few have ever heard of. Here more than 70,000 people, most of them Jews, were murdered by the Nazis and their collaborators. There are no gravestones. The bodies could be anywhere. But that's not the only secret buried here. More than 75 years ago, 80 Jewish prisoners attempted to dig a tunnel and escape. Only the entrance was ever found, leaving questions unanswered-- was it ever finished? Where did it lead? The answers seem lost to time. But can science reopen the investigation and help us understand not only this place, but the Holocaust itself?

TIMOTHY SNYDER

It's strange to say, but the Holocaust is actually much more terrible than we realize. And it happened in a way different than we think.

NARRATOR

For some, it is a history still unresolved. (several people saying, "Shalom") (indistinct conversations) These people are the children of a unique group of Holocaust survivors. Their fathers survived the killings pits of Ponar Forest. My father used to say that they started it just behind. Not that I ever doubted that the stories were the right stories. They heard stories of the tunnel. (woman speaking Hebrew) But with their fathers now gone, and no firm evidence, only questions remain. What really happened?

HAIM MATZKIN

It would complete the entire picture if they would find the tunnel. (speaking local language)

NARRATOR

Now two archaeologists, Richard Freund of the University of Hartford, and Jon Seligman of the Israeli Antiquities Authority, believe they can answer these questions. But doing so will take them to a place few would expect-- Lithuania. Armed with new technology... We now know we're going to follow that line back....their mission is focused on a renowned city of 70,000 Jews wiped out by the Nazis. The traces are almost invisible today. And with each passing decade, the story is further distorted by the lens of time.

McCLYMONT

We're picking up two hotspots.

NARRATOR

To unlock the hidden history of this lost city will require not one investigation, but three. The search begins where Vilna ended-- the brutal Nazi execution site known as Ponar. To this day, the location of multiple mass graves is still a mystery. The second piece of the puzzle is Vilna's great synagogue, devastated by the Nazis, erased by the Soviets after the war, as if to warn the Jews, "Don't come back." The last piece takes them back to the forest, and Vilna's final chapter, to find proof that the escape tunnel really existed. If successful, the team may uncover not just a lost civilization, but a turning point in the evolution of the Nazi killing machine. Today, few clues would reveal it. But more than 75 years ago, it was here in Lithuania that the Final Solution-- the systematic mass murder of six million Jews-- first began. Before the industrialized killing of the gas chambers in places like Auschwitz, the Nazis and their collaborators murdered Jews here by the thousands, one bullet at a time. They began killing 500, 600, 700 people per day. (gunshot) This is ground zero for the Final Solution. It is a painful history Lithuania is only now beginning to explore. The pieces were in motion by 1940. Lithuania was trapped under a brutal occupation by Stalin's Soviet army. With the Germans approaching the border, antisemitism, already simmering, exploded.

ELLEN CASSEDY

Right before the war, Nazi propaganda flooded the country of Lithuania, promoting the idea that Jews were communists, and communists were Jews, and that if the Soviet Union was moving tanks into the country it was because of the Jews. Now, in fact, most Jews were not communists, and most communists were not Jews. But that idea really took hold in the Lithuanian consciousness, and it was very, very damaging.

NARRATOR

Amidst the upheaval, the Soviet army began digging pits to store oil and gas just outside the capital, in Ponar Forest. Samuel Bak, now an internationally known artist, spent part of his childhood in the nearby village.

SAMUEL BAK

I was there. I was in Ponar in this dachu of my aunt. I remember this... kind of the noise of the digging of their construction that was supposed to be a big base for containers of gas.

NARRATOR

But construction was never finished. In June 1941, the Germans invaded Lithuania and pushed the Soviets out. In June the Germans attacked us. They bombed us. And on the 24th, they walked into our city. The Nazis soon found Lithuanian collaborators eager to help in the killing of Jews. They also found something else-- the freshly dug pits in the forest. Just days after the invasion, they brought the first victims to the site, where they were shot. (gunshot)

SNYDER

And this Holocaust by bullets, as it's called, it's how it starts. It's how half the victims die. But it's also the decisive moment when it's realized that something like this is possible.

FREUND

This was the tipping point. Because at this place they began systematically killing the Jews.

PATT

When historians try to understand, when did the Germans decide that the policy of the war would be total annihilation, total extermination of the Jews, they look at the summer of 1941 and they see a real turning point in this transition to mass murder.

NARRATOR

The killing was directed by Nazi troops known as einsatzgruppen.

JON SELIGMAN

We know the people's names. Martin Weiss was the head of that unit. And he was the person directly responsible for the management of Ponar. Under his control he had now 150 Lithuanian volunteers from the Lithuanian Rifle Association who went into another unit which is called the Special Ones. They were the ones who were directly responsible for the actual killing and the actual annihilation of the Jewish population on a day-to-day basis. (speaking Russian) (translated): Going to Ponar was death. That's what people said. There was no escaping.

NARRATOR

Today, trains still pass by Ponar Forest.

FREUND

You're hearing the trains going by. There were three ways that they used to bring the victims here. One was by truck, one was by walking, and one was by train. So when you hear these trains, you're listening to the sounds of the first moments of the Final Solution. (train horn blasts)

NARRATOR

Little evidence survives. The Jewish State Museum here is determined to preserve what still remains. Six burial pits have been identified so far. There may be more. There are as many as 12 burial pits here. But how to find them? German aerial photographs from the war provide one clue. More recently, a LiDAR study commissioned by the Jewish State Museum used laser imagery to strip away the foliage, confirming the six known pits. A large indentation in the ground nearby reveals a possible seventh pit. But they can't simply start digging.

FREUND

The biggest problem that you face is that there are people buried here. How do you excavate to find out which way?

NARRATOR

Geophysicists Paul Bauman and Alastair McClymont... You can see how deep that is. Very deep....are using a tool that is relatively new to the field of archaeology-- electrical resistivity tomography. The technology requires no digging at all. Instead, the team will essentially scan the ground in a narrow slice, generating a picture of the soil hidden below.

BAUMAN

We have these gadgets, these things that can see under the grounds. Our goal is to identify the area of the pit, the depth of the pit, and then we can calculate a volume in the pit.

NARRATOR

Once the volume is known, the team can then estimate the number of bodies buried within. The first step is to hammer a line of metal spikes into the ground. The spikes are then linked together with cables. A control unit powered by a car battery then fires hundreds of electrical pulses and measures the way the soil conducts electricity. The resulting measurements are then assembled into a detailed map revealing what lies below. To the trained eyes of the geophysicists, it can reveal where the natural soil ends, and any disturbance, like a mass grave, begins.

BAUMAN

It is a subtle signature. However, we're fortunate that in this environment that there's homogenous sand where everything looks the same. So even a subtle signature stands out very clearly.

NARRATOR

The entire process takes hours, as the machine sends electricity into the ground, slowly mapping the soil. Something's happening at... It takes multiple passes...

BAUMAN

How many meters do you think it could be off? Five to then, ten to 20?

NARRATOR

...before they finally start to see results.

BAUMAN

Oh, this is better! So that's good. It looks like we have a pit.

NARRATOR

The rest of the team is summoned, and Freund briefs the student volunteers. It's about 24 meters large, four meters deep. So it's a burial pit. If somebody asks you what is going on here, you can say there are about 5,000 to 7,000 people who are buried in this unknown pit. Thousands of people buried in this forest, murdered by the Nazis. But who were they? Today this city goes by its Lithuanian name, Vilnius. But for centuries, it also had another name, one rarely heard now-- Vilna, its name in both Hebrew and Yiddish, the everyday language of European Jews. They called it the Jerusalem of the north.

DAVID FISHMAN

That's an unusual title. There are only a few communities in Jewish history that got named "the Jerusalem of..."

PATT

Vilna was one of the most important cities in Jewish history, certainly one of the capitals of European Jewish civilization.

NARRATOR

Prior to World War II, Jews made up a large part of the city. Most people think New York is a very, very Jewish city. Well, that's 15%. But Vilna was, at its peak, 40% Jewish.

PATT

It was a center of Jewish learning, of Jewish culture, of Jewish politics.

NARRATOR

Six Jewish newspapers, museums, the largest Jewish library in the world. Esia Friedman was born in Vilna before the war. For me Vilna was the most beautiful place in the world. Everything was gorgeous. Any little synagogue that you went in was beautiful.

BAK

There was all this learning. And there was a very specific cultural character of the Jews of Vilna that was the result of the studies and the attitudes of a very famous rabbi who is called the Gaon of Vilna.

NARRATOR

The Gaon's legacy of scholarship, both religious and secular, came to permeate all of Vilna. But today, Vilna's most sacred places have vanished. This patch of soil was once the most important Jewish landmark in the entire city. For centuries, this was the site of the Great Synagogue of Vilna. Destroyed by the Nazis, the ruins were leveled by the Soviets, who sealed them away by building a school on top. Only fragments survive in museums today. Some of those fragments were recovered in 2011 when Lithuanian archaeologists dug three excavation pits next to the modern school. (speaking local language) (translated): The goal was to pinpoint more precisely the location of the Great Synagogue itself, and the main architectural features of the synagogue. The excavations uncovered pieces of the main worship area.

FREUND

What's amazing is it was right here, where the ark sat. And they found the column base, and the steps leading up to the main bema, where the Torah was read.

NARRATOR

Today, much of the worship area lies buried under the school. But the complex was far larger.

SELIGMAN

We've got to look at this whole complex as a sort of community center. You would've been coming in from the Jewish street over there. You would have been walking down the Jewish street, coming in the main courtyard.

NARRATOR

Dating back to the 16th century, the Great Synagogue was not the only synagogue in the city. In fact, there were more than a hundred. Then, as now, Judaism was diverse, ranging from ultra orthodox to secular. But the Great Synagogue, more than any other, was integral to the identity of Vilna. It was unmatched-- there was nothing like it. The complex housed the world-famous library, kosher meat butchers, and a communal well.

It also held another critical structure

the mikveh, the ritual bath required for observant Jews.

SELIGMAN

It potentially could be one of the oldest parts of the structure. So that's a really important aspect of the whole complex.

NARRATOR

Based on historical diagrams, Jon Seligman suspects the mikveh is under the playground. For the archaeological team, it is an appealing target. Mikvehs are great places to excavate, because people lose all their personal items when they're going into the bath. Recovering this lost world is a personal mission

for many on the team

Lithuanian archaeologists, Israeli volunteers, American students.

ALEX KLEINSCHMIDT

For me personally, my goal is to be able to contribute to mankind and to be able to say that I did something.

NARRATOR

For lead archaeologist Jon Seligman, the investigation is even more significant. His family once lived here. So this for them would have been the place they would have looked up to as the most important place within their own community. Most of them were murdered in the killing pits of Ponar.

SELIGMAN

Looking over my shoulder there's my grandfather, maybe, thinking "Good on you." And so for me that's something of great meaning.

NARRATOR

With no clues visible from the surface, the search for the mikveh begins with a technology known as ground penetrating radar. Harry Jol is the team's GPR expert.

HARRY JOL

So ground penetrating radar, or known as GPR, uses FM radio waves, just like we're listening to in the car here. We're actually putting those waves into the ground, they're reflecting off of surfaces, and that's what we're seeing in the radar.

NARRATOR

By measuring how quickly the signals are reflected back to the unit, GPR can reveal features in the ground that don't look natural.

JOL

Particularly in archaeological, you're looking for those right corners. Nothing in nature builds anything with a right corner. And so if we can figure out a feature that has a right corner, we can say, "Oh, that's a building, that's human."

NARRATOR

With scanning complete, the data is sent to California for processing while the team sleeps. By morning, the results are ready.

JOL

The data just came back. And what we're seeing here in these slices is some straight lines, and they're coming in at right angles. The only thing these could be is potential walls.

NARRATOR

Jol hands the data over to cartographer Phil Reeder.

REEDER

We look for all the existing maps and diagrams. and then what we're able to do is we're able to overlay them on top of each other, get everything in the same scale, and then we can add our data to that.

NARRATOR

When the GPR data is matched against the floor plan of the complex from before the war, the team knows exactly where to start. The first loads of soil go into the sifters. And almost immediately, artifacts appear.

FREUND

And now we have silverware. I don't think we're in a kitchen, although the possibility is that somebody was actually cooking here, because there's coals, there's burnt wood.

NARRATOR

Coins, pottery, tiles from the large heating stoves that once stood here.

SELIGMAN

You'd have, like, a stove which would be stoked from below and it would be be heating up the water, and the room itself-- the room would have to be warm as well. I mean, if you're talking Lithuania today, it's a nice sunny day but in the winter over here it's miserable. It's fantastic, and it's beautifully decorated.

NARRATOR

The tiles from the heater suggest they may be close to the mikveh-- close to discovering a key part of the Great Synagogue that was burned and bombed by the Germans during the war. In 1941, the 70,000 Jews of Vilna found themselves trapped. There was no escaping the Nazis.

MARKAS ZINGERAS

And then, of course, a sudden occupation of the Nazi Germany. So there was not much time to run away from Lithuania.

VADIM ALTSKAN

There were a few trains which left Vilnius, but many travelled on foot, and they couldn't even cross old Soviet-Lithuanian borders-- they had no proper documents. It was like a nightmare. No doctors, no going to school, no walking on the sidewalks. No food. The Germans immediately told us that we had to be marked. So we put on the yellow Star of David.

NARRATOR

Soon the door-to-door searches began, and people started disappearing.

ALTSKAN

And this is a time, it's late June, early July 1941, when Vilnius is a very dangerous place for Jews. They snatch from streets, they taking by so-called hapuns-- this is Yiddish word for people who are catching.

NARRATOR

Ten weeks after the invasion, the remaining Jews were forced into one of two ghettos, including young Samuel Bak.

BAK

One day the Lithuanian police came and said, "You just take with you what you can carry and go out into the street."

RACHEL SHARON

In one apartment, like 50 peoples here. One by the other, one by the other.

FRIEDMAN

One Saturday morning, my mama heard screaming. She opened the door. And there was an elderly man from my street being shoved. These barbarians were pushing an old man. And then they went after my friend. Nahama was her name. She had a sister and a baby and parents. And the little girl was crying, so they bayonetted her and threw her out.

NARRATOR

Children were regularly targeted.

SHARON

My sister was two years younger than I. Her name was Shaindele. Shaindele, in Hebrew, it mean yapheh. In English, it "beauty." And she was a real beauty. In that morning when I kiss her, I said to her, "I will no... never see you again." And I didn't see her again. It was my last time that I saw her. Like an angel.

FRIEDMAN

My mother was brave. I don't understand it. She went to work, but she would hide me in an attic. And she would go to work. I was hungry. And she would always tell me, "Not a word." You know, "You have to stay quietly." And she was hiding me out. And this is how I lived for what I thought was a long, long time.

NARRATOR

Also hiding inside the ghetto was a group of Jewish rebels determined to fight back. Known as the FPO, or simply the Partisans, their leader was a man named Abba Kovner.

PATT

It's no coincidence it's in Lithuania, it's in Vilna, that we first see somebody like Kovner, who says, "This is not isolated. "This is something that is going to happen to every Jew in Europe."

NARRATOR

The Partisans began to stockpile weapons, hoping to hold on until the Soviets returned to drive the Nazis out. In 1943, the FPO snuck out of the ghetto through the sewers. They began launching attacks on Nazi targets in the forests around the city, including Ponar. By this time, the Nazi execution site here had been active for two years. About 70,000 Jews had been murdered, along with thousands of suspected communists and other people the Nazis deemed enemies. The burial pits were nearly full. It was damning evidence, and the Russians were coming.

FREUND

By December of 1943, the Nazis knew that the Russians were on the border, ready to take back Lithuania. They had committed, by that time, nearly a hundred thousand atrocities. Many of the people had been shot, and they were kept in these burial pits, but they now needed the evidence to disappear into ash.

NARRATOR

Only a few thousand Jews were left in prisons and small labor camps in the area. The Nazis gathered 80 of the healthiest and brought them to Ponar, not to be shot, but to work. Much later, their children learned the story of their ordeal.

HANA AMIR

He was the youngest one, my father. There were 80 people that worked. There were four women that were in the kitchen.

MATZKIN

During the first months, they were asked to... to cut down trees. And they were not told what the trees were to be used for. Towards the end of 1943, somewhere in December, the beginning of '44, they were told what the purpose of those logs were.

GOL

The German commandant of Ponar said, "The reason that we brought you here "is because all these Lithuanians "committed this horrific crimes against the Jews, and we want you to clean that up."

MATZKIN

Their job would be to dig them out and burn them.

NARRATOR

Dig out the thousands of bodies and burn them.

GOL

The diggers, the burners, everybody had their own task. The younger people were charged with pulling out the gold teeth.

MATZKIN

He said the corpses were already decomposed, but he recognized some of them by their clothes. I think he found his two children, I'm not sure. But I know for sure that he found his wife and he found the other family members. They used to burn, he said, about 200 corpses on each layer of wood, of logs. They used to put, like, ten layers, so it was about 2,000 corpses, plus or minus, a day.

AMIR

He said that in one big hole they counted between 22,000 to 25,000 bodies. My father said you can try to imagine what... You can't imagine it.

NARRATOR

The stacks of bodies were so large, ramps were needed to build the topmost layers. This is the burning brigade's bridge that they used. And the would be able to grab the bodies, and then they would be able to throw them onto pyres.

MATZKIN

As a child, I remember him waking up and shouting in Lithuanian, "Pajarna," which is fire or something like this. Burning or fire. He was really haunted by those pictures.

SABINA DOMBA

(speaking Hebrew) (speaking Hebrew) She says that in fact her father didn't tell her very much. He actually was... he was silent most of the time. and he would sit silently and chain smoke. My father, afterwards, kept on washing hands, all the time.

FREUND

And in December, January, they all realized, those 80 Jews-- 76 men, four women... that when they're finished they would be the last victims. So they hatched a plan.

AMIR

He said that, "All we thought is that someone will survive and tell the world what's going on, what happened here."

FREUND

And they started digging an escape tunnel for 76 days.

GOL

She said there were two of them at the time. One would dig, and another one would ferry the dirt back into the bunker. (speaking Hebrew) She says that the candle they were using for lighting would go out-- wasn't enough oxygen to keep the candle going. So her father set up an electrical system with a lightbulb. (translated): The tunnel, despite being small, had to be correctly engineered. One had one had to understand the distribution of pressure and so on. My grandfather had a degree in engineering, and could be useful in the construction.

NARRATOR

These stories testify to the existence of a tunnel. But so many years later, can it be found? We do a lot of tunnel detection, and it's really difficult. And especially a tunnel like that where it's just... it's hand dug, it's small. There's nothing in it. There's no metal supports. It's surrounded by sand. Very improbable. But can new technology help?

BAUMAN

So when I come to these projects, I don't expect everything to work and us to find everything we're looking for. I just want to have some success.

NARRATOR

The team has only one clue to go on-- a Lithuanian excavation in 2004 that identified the entrance.

FREUND

The entrance to the tunnel was found in the original excavations they did. But they couldn't find the continuation of the tunnel-- that was the key.

NARRATOR

The first thing the geophysics team needs to figure out is the direction the tunnel would take, if ever completed. Architect Ken Bensimon spent his career designing prisons. Our design was to prevent escapes, and to prevent the design of tunnels. Ruling out where the Lithuanians already excavated, and knowing the diggers would not have backtracked across the pit, Bensimon has flagged an area for examination. And on their very first run, the team gets a surprise.

BENSIMON

Wow. It's exactly there.

NARRATOR

One hotspot stands out. It looks like the cross section of a collapsed tunnel, about 130 feet away from the previously discovered entrance back in the pit. Most of the soil-- colored blue-- is too dry and sandy to conduct electricity very well. But the soil in the collapsed tunnel is looser and holds more moisture, conducting more electricity and generating the signal they see on their screens.

BAUMAN

It rains here a lot. Here you even a ditch leading into it where it's collapsed, and even if it's collapsed it's not going to be as compact as the originally sand that was laid down. Okay.

NARRATOR

It's not definitive though. They need to verify this signal is a segment of a tunnel. So they decide to scan the entrance found in 2004 and check if the images match. So this is the area where the tunnel began. The entrance is about four feet below where I am standing right now. Though the pit is empty today, a small hut stood here, later sketched by one of the survivors.

GOL

They were told to build their own living quarters, basically said that the German commandant of Ponar said, "This is where you will live."

NARRATOR

Climbing out of the pit to escape was impossible.

MATZKIN

The Germans put a lot of mines. So they could not really try and escape. And he always described that at the end of the day they were brought down with a ladder to the bottom of the pit. The ladder was taken out, Was taken away so there was no way they could climb it up.

NARRATOR

Their only chance at freedom was to dig through the floor.

MATZKIN

And they had like a cupboard and the cupboard used to cover the entrance to the tunnel.

NARRATOR

This is what the geophysics team will scan for. When they process their data, the tunnel entrance inside the pit shows up clearly... in exactly the same spot where the Lithuanian team found it in 2004. Oh, my God! (laughter) There's a resistivity section. We have a slightly more conductive anomaly. Equally important, the signal matches the first reading they got 130 feet away, roughly the length of the tunnel according to the survivors' stories. Oh yeah. Oh yeah. Now we know exactly what we're looking for. It seems they have the beginning and end of the tunnel. But can they find the rest of it?

BAUMAN

Lots and lots of naysayers that will say, "Any two points make a line, show me a third point." So yeah, I think we need a third point to convince everybody.

NARRATOR

Months before the tunnel was begun, in September 1943, the Germans begin killing the last ghetto residents, a process known as "liquidation."

FRIEDMAN

So my mother, she always had another plan of what would happen. And she pushed me over like a wall or a hall or wherever. But you know what she said to me before, in Yiddish? (speaks Yiddish) Which means, "My child, never forget that you're Jewish." And she pushed me out.

NARRATOR

Sam Bak was taken with his father to a work camp. But for children, it was no safer than the ghetto.

BAK

So about 200 kids that were in the camp were killed, and my father brought me out to the gate of the camp carrying me in a sack. Therefore my last memory of my father is the feeling to be on his... oh his shoulder, kind of a physical feeling of his presence. I don't even know if the voice of somebody shouting "Run, run, run" when they liberated me from the sack, I don't even know if it is his voice or somebody else's voice. But then he was just killed a few days before the Russians arrived.

NA

In 1944, the Soviets drive out the Germans, annexing the country. They would rule for nearly 50 years. In the Great Synagogue yard, the archaeology team finds what appears to be a remnant of the Soviet era. Yeah, do you know what it is? Yeah... (makes gun sound) from gun.

MANTAS DAUBARAS

It was obviously shot because of the dots over there. I do believe it's Russian.

NARRATOR

A Russian-made bullet from the post-Nazi era when the few remaining Jews, alongside other minorities, had to endure the Soviets' attempt to stamp out their religion and culture.

FAINA KUKLIANSKY

It was not so easy in the Soviet time. We could not go to synagogue. But you know, the people were so anxious that they wanted to have their culture so much.

NARRATOR

Fearing their precious artifacts would be destroyed by the Soviets, Jewish leaders sent them away. Today, one precious treasure has returned.

JUDAH PASSOW

In 1960, my father came to Vilnius, where he met the leaders of what was left of the Jewish community. And at this meeting, they produced this scroll and they pleaded with him to take it out to the West for safekeeping.

SELIGMAN

That's extraordinary. These are valuable possessions of every community-- these really are the most important possessions of every Jewish community, were the Torah scrolls.

NARRATOR

The Torah will be authenticated while the team returns to work. They only have two days left on their permit to find and document the mikveh, the ritual bath. But they've uncovered an important clue.

SELIGMAN

We have an arch, you can see the bricks over here. What kind of depth do we have right now?

MAN

Roughly 1.5 meters.

NARRATOR

With the clock ticking, the team digs in shifts. And then a lucky break. Literally.

SELIGMAN

Oh, my goodness.

NARRATOR

They clear away a small hole.

FREUND

If we can get in underneath, then we may have won the lottery.

SELIGMAN

Have you hit the floor? Right now I did. How much is that? 360. 360-- yep, that's deep. It's about ten-and-a-half feet.

NARRATOR

The hole is just large enough to fit a GoPro camera. You can see brickwork.

MAN

A wall.

SELIGMAN

Like a wall or something.

MAN

Okay, so we are going down.

SELIGMAN

I think that's pretty clear that's a heater, it looks like a water heater. We're standing in the corner of the vault. The line would continue more or less in line with where Jorgas is standing over there. And around about three or four meters in that direction. And somewhere around about close to the back wall we have a heater. Metal heater, which is heating up water.

NARRATOR

A water heater, likely for the bathhouse and mikveh.

SELIGMAN

That's the fun of archaeology is you've got no idea what you're going to find down there. No, it's the first time I've actually seen something like that. It's been a good day.

NARRATOR

A good day indeed. They've found an intact piece of the great synagogue complex.

SELIGMAN

It's absolutely successful. We will find more, I hope, in the future, and that's the way archaeology works. You find a bit now and you come back next year and you find the rest.

NARRATOR

At Ponar Forest, where the Nazis murdered about 70,000 people, the geophysics team is within striking distance of finding the escape tunnel. They found two cross sections, but they need more evidence to prove that it was actually completed and used. I'm going to split the difference between these two.

MAN

Yeah.

NARRATOR

A sudden rainstorm might actually help.

BAUMAN

It's a lot easier to get current into wet sand than dry sand, so the rain actually works in our favor.

NARRATOR

If they find it, they will have tangible proof for what have been only stories handed down from the survivors to their children.

FREUND

Their accounts are riveting. Because they give us detail. And on the last night of Passover, April 15,

00 and 10

00, they knew that there was great danger. But they were going to try to get through the forest without making too much noise. (twig snaps)

AMIR

The guards heard the steps, and that's when they start shooting.

GOL

And the guards started firing indiscriminately. They didn't see anybody, didn't know who they were firing at. My father was able to climb out of there and sta running. (gunshots)

NARRATOR

Of the 80 prisoners, only 11 escaped and made it through the war.

FREUND

It is one of the most horrific escapes that we have in the Holocaust, but it also is, I mean, a great testament to the courage and survival.

NARRATOR

Once in the forest, they were found by Abba Kovner and the Partisans. Some joined the fight against the Nazis.

AMIR

My father said, "We wanted to fight, we wanted revenge."

NARRATOR

Years later, Abe Gol's father ended up in America. The engineer, Yuri Farber, returned to his birthplace in Russia. Hana's father, Motke Zaidel, settled in Israel, as did Haim's father and the rest of the survivors. For decades, their words were the only evidence for the tunnel. Now modern technology is about to prove the story true. The inversion's finished? Yep. Because there, on the screen, appears the third piece of their tunnel.

BAUMAN

This is astounding. Like as good as we possibly could have hoped for. That's our third point. Oh gosh. Oh!

FREUND

We've found a major part of the tunnel. And there's something extremely personally moving about knowing what these people must have gone through in those 76 days.

NARRATOR

Two last scans provide the final confirmation. So the tunnel is many feet below where I am standing right now. It extended about the same level under this hill, out in this direction. Our technology indicates it's approximately on this alignment, under this hill... and continued for about 90 to 100 feet. And the exit is somewhere beyond this area here. The news of the discovery soon makes international headlines, reaching the survivors' children in Israel, who are eager to see the proof of their fathers' stories. (speaking Hebrew)

FREUND

See all the blue? That's sand. And we have five slices that we did of the tunnel. Where is the entrance to the tunnel? The tunnel is at the corner here.

AMIR

It's just like my father used to do with the hands, "We dug just like this." Just behind the kitchen.

SELIGMAN

This is a very special opportunity to look at what happened at that place. It was something that you felt was really unreal. And you thought, well, they mystified some of it. And then, everything is here. The moment I saw it, I washocked. This actually closes the full circle for me. Absolutely.

NARRATOR

Modern technology has brought them the closure they thought they would never have. But the civilization known as Vilna is gone. More than 95% of the Jewish community of Vilnius was destroyed, and thousands of other lives were taken. A vital culture, hundreds of years old, embodied by the Great Synagogue at its center, is extinguished. (praying in Hebrew) The Torah scroll, back from safekeeping, has been authenticated. It is one of the last surviving pieces of Vilna, now kept in one of the city's only active synagogues. As time passes, memories of Vilna and its people will fade and die out. But the truth of what happened here has not been forgotten and now, through the proof that science has given us, it will never be erased. This NOVA program is available on DVD. To order, visit shopPBS.org, or call 1-800-PLAY-PBS. NOVA is also available for download on iTunes.