Lying to the west and bordering Brandenburg, Spandau feels almost like a different city even if it has been part of Berlin since 1920. The Italianate Citadel at its heart stands on an island where the rivers Spree and Havel meet. This is the oldest non-Christian building in Berlin and it is now used mainly for exhibitions. Whereas most parts of Berlin feature Wilhelminian or modern architecture, Spandau's old town reaches further back into the past. Its Nikolai church, built in the gothic style, dates back to about 1200, as do some of the oldest parts of the fortress. The old town has many restaurants and excellent shopping. Each year, a traditional Christmas market is held in Spandaus narrow streets. The district is not without its forests and rivers but it is also home to a German new town, the Siemensstadt, built by the famous German teleconmunications company to house its workers in the 1920s. The U7 underground and the S5 and S75 overground lines run through Spandau while the U2 underground crosses the eastern part.