BERLIN — “It was a very touching moment. It brought back memories of a time when as young man I had sworn to fight the wall.”
Those were the words of Carl-Wolfgang Holzapfel, a 73-year-old retiree who says that he helped dig a tunnel under the Berlin Wall in the 1960s.
The entrance to the tunnel, a desperate attempt to pierce the Iron Curtain and reunite a divided family, was unearthed this week after laying hidden for more than 50 years.
The discovery has fueled memories of a dark chapter in Berlin’s history.
When East Germany sealed off its section of Berlin in August 1961, many families and friends were separated. Shortly after, a group of four West Berliners, responding to the call of a man named Gerhard Weinstein, found an abandoned railway shed near the wall that split their city, and began digging.
According to Torsten Dressler, an archaeologist who found the tunnel entrance, they wanted to reach the basement of an apartment building on the other side of the wall. The tunnel would then be used to get Mr. Weinstein’s young daughter and some of his in-laws and friends to the West. The shed and the basement, a stone’s throw from each other physically — through a world apart politically — sheltered the group from border guards and were meant to provide a secure entrance to the escape route.
It was not to be. As the 260-foot tunnel, running about 13 to 16 feet under the current surface, neared completion, the Stasi, East Germany’s feared secret police, intervened. They shut down the tunnel and arrested all of the 21 would-be fugitives.
The tunnel was filled in, abandoned and forgotten, only to be discovered recently when workers at the Mauerpark, a green area near the former buffer zone around the wall, found it during building work.
About 75 tunnels were built under the wall during its three-decade existence, many of them around Bernauer Strasse. Residential buildings nearby provided handy shelter for digging and for entering the passages.
One escape that received widespread attention was filmed by N.B.C. in 1962. The network provided money for an effort by students in West Berlin to connect two cellars on either side of the wall. The resulting documentary, called “The Tunnel,” related the escape of 29 men, women and children, and it raised questions about the journalistic ethics involved.
In the autumn of 1964, 57 people from the East escaped through a tunnel that started in a disused courtyard bathroom. But this escape marked a turning point. An East German border guard was killed in a gunfight between the security forces and those helping the escape on the Western side. The 21-year-old guard, Egon Schultz, became a hero in the East after his death, leading many in the West to question the wisdom of promoting such crossings.
For a long stretch, Bernauer Strasse runs parallel to the site of the former wall. The street is also home to the Berlin Wall Memorial.
Mr. Dressler, the archaeologist, says there has been a shift in attitudes about preserving the wall. At first, there was a zeal to eradicate all signs of the hated barrier. But a push to document — and, in some cases, preserve — the border’s infrastructure has gained traction. In the mid-2000s, a group of archaeologists, preservationists and city planners started compiling a list of the structures involved in dividing the city.
One finding: The wall wasn’t always in the same place.
The site of the tunnel entrance that was recently found, for example, was not always in West Berlin. A year before the fall of the wall, the border was moved about 165 feet to the west in a land swap that the East German government apparently hoped would prevent people fleeing from a nearby soccer stadium.
Identifying remains of the wall and of escape tunnels like this one is a crucial part of ensuring that history — and the people affected — are not forgotten, Mr. Dressler said.
“It was a tunnel that had dramatic effect,” he said. “Twenty-one people were arrested as a result of that tunnel, and one woman died while she was in prison.”