Behind a nondescript steel door next to a busy subway platform, a hidden passage leads to an underground complex straight out of the Cold War: a concrete bunker designed to shelter thousands of people from a nuclear attack.
The chances of World War III breaking out in the German capital seem remote these days, nearly 18 years after the collapse of the Berlin Wall. But the well-preserved bunker remains ready just in case. Storage rooms contain bunk beds, thin blankets and polyester jogging suits for 3,500 people, along with 70 bassinets for infants and several stacks of body bags.
The bunker at the Pankstrasse subway stop in a working-class neighborhood of Berlin is part of a spaghetti network of intact underground shelters dating to the city's tumultuous years during the 20th century. Although Berlin has undergone an extensive urban renewal above the surface since the Wall's demise, the capital has only recently begun re-exploring its subterranean roots.
This year, the Berlin Underworlds Association), a nonprofit group founded 10 years ago, is expected to guide more than 100,000 visitors on special underground tours. More than 300 bunkers remain from World War II, and while many are filled with debris or blocked from the outside, others are in pristine condition.
Dietmar Arnold, the organization's co-founder, said Berliners had tried hard in the past to move beyond the painful years of World War II and the subsequent division of the city. But recently, he said, there has been renewed interest in how the city coped during those times, including people's memories of being forced to burrow below ground to survive.
"We are really pioneers in this direction in Berlin," Arnold said. "It was the same with the Berlin Wall. People said, 'Let's get rid of it, cover it up.' It's really a shame for the city. I can't show my daughter, for example, how things were back then. It's a big shame, but the thinking has started to change."
Last June, the Berlin Underworlds Association broke a long-held German taboo by erecting a marker in the city center that points out the exact location of the most notorious underground site in the city: the Fuehrerbunker , the fortified shelter where Adolf Hitler sought refuge from Allied bombers and then killed himself in the waning days of the war.
For decades, German authorities had sought to conceal or minimize the site, saying they feared it could turn into a shrine for Nazi sympathizers. Until last summer, the only public acknowledgment of the Fuehrerbunker's location was a small placard outside a Chinese restaurant in the vicinity of the site.
"This is one of the most symbolic places in Berlin for the crimes the Nazis committed, and we want to make sure people know the whole truth about it," Sven Felix Kellerhoff, author of a book about the Hitler bunker, told reporters at the unveiling of the marker last June.
Berlin Underworlds members and other underground enthusiasts said they had struggled for years to get city hall officials to cooperate with their efforts to re-explore and reopen the capital's tunnels and other hidden spaces. "They called us 'bunker kissers' and 'concrete romantics,' Arnold recalled. "We had a lot of fights with the government. They would only let us operate in dirty corners of the city, like we were neo-Nazis."
Recently, however, Arnold said, there has been a change of thinking at city hall, which has come to appreciate the tourism potential of Berlin's concrete bowels.
Ingeborg Junge-Reyer, the city senator responsible for urban development, praised Berlin Underworlds for its work. In addition to giving tours of selected bunkers and other sites, the group runs an underground history museum. Among those who took the guided tours last year were Hollywood couple Angelina Jolie and Brad Pitt and German President Horst Koehler.
"Not many people know how Berlin looks underground, and it is not accessible for the most part," Junge-Reyer said. "But people in Berlin are eager to have a look at tunnels, at vaults, at the history of their city."
During World War II, Berlin had an estimated 1,000 underground bunkers to shield its residents. By the end of the war, more than two-thirds of them had been destroyed. Many of the others were later sealed off or forgotten.
Starting in the 1970s, the West German government began a program to refit some of the bunkers as nuclear fallout shelters. The refurbishing was meant to reassure the public that the city had a viable civil defense plan in case World War III broke out.
In the end, however, there was enough fallout shelter space for only about 27,000 West Berliners out of a 1970s population of about 2 million, according to Kay Heyne, a Berlin Underworlds tour guide. Far fewer shelters were opened in East Berlin, he said, with nearly all the beds reserved for the Communist Party elite.
Most of the refurbished shelters remain in good operating condition and are fully stocked with supplies. "Today, if there is some kind of war, they could still be put to use," Heyne said as he showed off the warren-like spaces of the Pankstrasse shelter. "We had to agree to keep this bunker in operating condition, in case of war."
In addition to giving public tours, Berlin Underworlds has an active exploration program. In 2000, the group inspected a bunker underneath Tempelhof airport and found a Nazi archive containing files for 4,000 people who had been forced into slave labor under the Third Reich. Researchers used the files to track down 21 survivors in Ukraine, who received compensation from the German government as a result, Arnold said.
By examining old maps, the group has discovered several tunnels and forgotten storage rooms connected to Berlin's subway system. Hundreds more remain undetected, according to Arnold, an engineer and urban planner by training who now devotes his time to leading the group and writing books about the Berlin's subterranean world.
"In the underground, we know there are a lot of shelters, but we just don't know how many," he said. "We have a lot of work left to do."
Special correspondent Shannon Smiley contributed to this report.