I am a child of the 1980s, and as such, the end of the Cold War and the Soviet Union happened around the time I came into political awareness. It's only to be expected that something of that magnitude would have influenced me a lot.
I've been to Berlin 3 times now. Once for 3 days in 1997, once for a week at Christmas 2007, and most recently May 2010. At Christmas 2007, I learned about a consequence of the Berlin Wall that I'd never heard of before: Geisterbahnhöfe: ghost stations.
The public transit system in Berlin was started in the 1890s, and the rail system several decades before that. So when SED-president Walter Ulbricht built the wall (which he rather famously denied plans for), the two subway lines and one street-train line that crossed from West to East to West were closed down, and no one could get on or off at those stations. (With exceptions: at Friedrichstrasse there was a border station, where the West Germans could pay a fee and visit family in the East.)
Berlin wasn't divided in half on a north-south line. The Soviet sector encompassed a certain set of districts, and Mitte, where the Brandenburg Gate and Potsdamer Platz are located, bulged out a bit into the west.
The Soviet/SED leadership called the wall an "anti-fascist protection wall," a fine bit of doublespeak: while they claimed to want to keep the "fascists" in the West out, they really wanted to keep the East Germans in. And, of course, someone could hop onto a train at, say, Alexanderplatz, and get out in the West and never look back. So, of course, they walled off the entrances and stationed border police inside, to prevent people from escaping through the rail tunnels.
Of course, people tried, and some were almost successful. People also built tunnels under the Wall, usually from a starting point in the west (in somebody's basement, frequently), but they were also discovered eventually.
Then in 1989 and 1990, these stations that had been abandoned for close to thirty years were in terrible disrepair, and it took years to reopen them all.
When I learned about the ghost stations, I knew I had to write a story about that. It took a while to find it, but I finally did. "U8: Alexanderplatz (1989)" is the result.