The cathedral is surrounded by the Old Town of Lausanne, including Maire Castle, which was built between 1397 and 1427 and the 17th century town hall. The Ale Tower, which was built in 1340, and the tower of the bishop's castle in Ouchy, dating back to the 12th century, are the last remnants of the medieval city wall, which had about 50 towers. One travels most comfortably between the various parts of the city of Lausanne using the Metro, a subway which runs underground most of the time and is remote controlled, the first of its kind in Switzerland.