Off the beaten path is where Claus-Dieter Steyer feels most at home. He tells DW how he came across Berlin's best-kept secrets - and why he's now sharing them with curious tourists.
DW: Mr. Steyer, which secret location in Berlin impresses you most?
Claus-Dieter Steyer: The underground chapel in the Olympic Stadium. When you enter, everything gleams with gold. It was constructed in 2006 so that soccer players would have a placed to pray before or after a match. Actually, it's empty most of the time. But it's possible to hold a wedding there. For me, it's a very fascinating secret place.
After the publication of your book, it's hardly a secret anymore.
There are many international forums that focus on lost or hidden places. The scene has committed to not mentioning the precise whereabouts of the locations, only to say something vague like "in the north" or "near Berlin."
The objective of my book is a different one: I want to reveal the precise locations and how to get there because I want people to experience the places. That's why I've published locations in all of Berlin's districts in my excursion guide. These sites represent different eras: pre-World War II, during the war, the post-war years, the building of the Berlin Wall in 1961, and the fall of the Wall in 1989.
Can you tell us more about exactly which sites are included?
These are destinations that are not mentioned very thoroughly in the typical travel guides, but are still very exciting, like Tempelhof Airport. It was nearly finished in 1939 and was the biggest building in the world at that time.
Just like many other buildings in Berlin, it contains a kind of underworld with more than 100 air raid shelters, some of which can be visited. Among them is the film bunker, in which millions of Nazi film recordings were stored. The Red Army bombed the bunker's main door on May 2, 1945 and the nitrate film material burned like tinder. Everything was destroyed. The walls are still covered with soot.
Practically unknown is the architectural experiment that Hitler and [Nazi architect Albert] Speer carried out in Schöneberg in the middle of Berlin, just a short walk from the Südkreuz train station. It was a colossus, stretching 12 meters (39 feet) above the earth and 18 meters beneath it. Visitors can even go inside. It was built by French prisoners of war.
How did you find out about this place and its history?
By sheer coincidence. I once visited an exhibition about how the Nazis planned to reconstruct Berlin, which was to become the world capital: Germania. There I learned that Hitler and Speer had carried out some experiments to find out how soft the ground was beneath the city and whether it was stable enough to support the monumental structures they had planned.
The Schöneberg colossus was part of the discussion. It was referred to as a "heavy load body," which I found fascinating. They wanted to use it to test whether they could build a giant triumphal arch - three times as large as the one in Paris, and the names of all German soldiers killed during World War I inscribed on it. Within the next two years, the structure sank only 19 centimeters deeper into the earth, so it would have actually been possible to build the arch - but that never happened. Later, people tried to remove the colossus, but it didn't work. Now we can say, thank God it didn't.
How did you manage to enter buildings that were completely fenced in, like the former hospital for members of the East German government?
It helps to be friendly. Some of these buildings are under surveillance. If you register first, sometimes you find a way. And sometimes it helps to simply talk with the guards about the weather and then ask them, "Well, what are you guarding here?"
Another trick is to take along your bike. Cyclists are unsuspicious by nature. If you don't have a bike, you can rent one in Berlin.
Did you have any difficulties along the way?
Sites which were too difficult to access are not included in my guide as recommended destinations. There are plenty of other secret places that are accessible to tourists.
Which sources did you use when you wrote your book?
Contemporary witnesses are very important for me, as are church archives, which survived the war and the division of Germany. And the clergymen tend to know who else to ask. Another useful source are small, local museums that are only open one or two days a week and contain historical treasures.
Is it also your intention to point out the value of hidden and secret sites so that they will be better protected against destruction or unnoticed decline?
Once people are on the road with my guidebook, they automatically start asking questions. Then politicians and property owners will have to take action. There is, for example, an engine shed from 1890 that is slowly falling apart. I could imagine a theater troop or a vegetable market moving in there. Or a tourist comes with my book in hand and says, "I always wanted to own an engine shed!" - and then he does something with it. That would be great.
The Berlin book is the latest in your series about secret places, which also includes Mecklenburg-Western Pomerania and Brandenburg. Where does this passion of yours come from?
My home town is Freiberg in Saxony, an old mining town near Dresden with a lot of underground paths that you can drive into. That left an impression on me. In Brandenburg, I discovered underground bunkers from World War II and especially from the East German era. I wanted to tell people about them. Now I look for secret places all over the world.
Your Berlin guide mostly deals with sites from the 20th century. Only the Pfaueninsel ("Peacock Island"), which served as a getaway destination for the Prussian kings, doesn't quite fit in.
The Pfaueninsel is a very popular excursion destination, especially for Berliners from the western part of the city. And it has a long history: It used to be a castle for Prussian kings; then the closing ceremony for the 1936 Olympic Games was held there with all the important people in the Nazi regime; in the 1960s the famous Edgar Wallace thrillers were filmed there.
Nowadays, the only person living there is the former garden director of the castle foundation. He once told me that there is a secret place, a path leading to the center of the island deep under the ground. The entrance is a door right next to a very old oak tree which can be identified on old copper engravings dating back to the early 19th century. You have to ask for the key to the door. Apart from that, your imagination knows no limits.