Siena is an Italian city located on three hills connected by streets forming a 'Y' shape intersecting in Piazza del Campo, a large shell-shaped central square. The city preserved its Gothic architectural style from the 12th-15th centuries despite a devastating plague in 1348. Piazza del Campo contains the town hall, bell tower, fountain, marketplace, cathedral, and other buildings and is used for horse races and gatherings. Siena is divided into 17 neighborhoods called contrade and is surrounded by fortified walls with 15 gates.