Beneath Berlin's streets lies a forgotten world of bunkers and tunnels that tell tales of cruelty, suffering, escape and espionage.
Foreign visitors seeking remnants of the city's violent 20th century history search in vain for two of the main attractions -- the Wall and Adolf Hitler's bunker.
The Wall was torn down, save for a few short crumbling segments, and Hitler's bunker is covered by a car park.
But some of the 1,000 World War II bunkers are intact and accessible, their echoing corridors, propaganda posters and instructions in Gothic script giving a sense of a past most Berliners would prefer to forget.
Luminous paint strips mark the way to emergency exits and cranks for manual air filters jut from the gray concrete. In one bunker, the walls are corroded by quicklime used to cover the dead from street fighting in the weeks before Berlin fell.
One bunker, next to the Gesundbrunnen underground station in central Berlin, contains suitcases, helmets, uniforms, bunk beds and a trove of items gathered from sites by members of the "Berlin Underground Association," which explores bunkers.
The Gesundbrunnen bunker was meant for ordinary citizens and is one of two sites where the association, made up of unpaid enthusiasts, conducts guided tours.
The bunkers of the Nazi elite, located under the city center between the Brandenburg Gate and Potsdamer Platz, in what used to be the Cold War wasteland between East and West Berlin, have been sealed for fear they may become neo-Nazi shrines.
"The city would rather not deal with its Nazi past buried in the ground," said Dietmar Arnold, a local historian who has explored the bunker system and leads tours.
"But we've noticed a lot of tourists come here and ask `Where is the Berlin Wall?' You can hardly show them anything. Then they ask, `Where was Hitler's bunker?'"
Arnold said it was "scandalous" that none of the city's bunkers had been placed under heritage protection. It would even be worth re-opening Hitler's bunker, he said.
The one-storey bunker measuring 15m by 20m lies underneath a car park in front of a modern block of flats close to the Holocaust memorial now under construction.
Communist authorities re-opened it in 1985, destroyed its 4m thick ceiling, and buried it again.
Opening the bunker would remove the mystery surrounding it, said Arnold. "If you combine it with a proper historical exhibition and have someone at the door to make sure only the right sort of people get in, it could be a significant site."
Petra Reetz, spokeswoman for the city's planning department, defended the decision to keep the bunker closed. She said, "We don't want a site where someone gets the idea to put up a candle on Hitler's birthday."
The so-called "Driver's Bunker" nearby, built for Hitler's chauffeurs, was uncovered in 1990 during a search for unexploded World War II bombs.
It contains giant wall paintings of SS troops holding large black shields to protect blonde women and children.
"Those SS comics are a curiosity and were documented and photographed. We consulted historians and concluded this was not of historic value," said Reetz. So the city filled the bunker with sand and sealed it.
Reetz denied Berlin's city government was ignoring its past by neglecting the bunkers.
"Bunkers make an important statement -- if you start a war don't be surprised if it comes back to you," she said. "But Berlin is penniless and has to make priorities. Besides, history stares you in the face above ground everywhere in this city."