The pretty town of Potsdam (www.potsdam.de) is 45 minutes by train from Zoo station. Its main attraction is Park Sanssouci (0331 969 4202), with a grandiose 18th-century palace surrounded by grounds that are fine for a stroll. The other major point of interest is the Filmmuseum (Breite Strasse 1A, 0331 271 810), which documents a century of German cinema. A 20-minute walk over the Lange Brücke and down Albert-Einstein-Strasse are the old studios of Babelsberg (August-Bebel-Strasse 26-53, 0331 721 2717), the centre of the old film industry. In the 1920s this was the world’s largest studio outside Hollywood, producing masterpieces like Metropolis and The Blue Angel.