The Berlin U-Bahn (underground railway) opened in 1902.

Pictured here is a train entering the Spittelmarkt station in 1908.

During the Second World War, U-Bahn travel soared as car use fell, and many of the underground stations were used as air raid shelters.

After the war, East Germans were prevented from riding on the U-Bahn into West Berlin.

Here we see Soviet soldiers storming the Berlin U-Bahn in 1945.

This is a photo of a train leaving Nollendorfplatz, one of the original stations of the Berlin U-Bahn.

In 1989, following months of unrest, the travel restrictions placed upon East Germans were lifted.

There are several stations, platforms and tunnels that were built in preparation for future U-Bahn extensions, as well as those that have been abandoned following planning changes.

Many of these abandoned tunnels and platforms are used for the storage of props and for fire fighting exercises.

This is the Subway station Innsbrucker Platz, prepared for the U10 line, which was never built.