Situated at the southern tip of the Istria peninsula, Pula is known for its mild climate, smooth sea, and unspoiled nature. The natural beauty of Pula's surrounding countryside and turquoise water of the Adriatic have made the city an internationally popular summer vacation destination. An area administrative center dating back to the ancient Roman era, Pula has a long and fascinating history. It has at various times been under the rule of the Romans, Ostrogoths, Venetians, Hapsburgs and Italians, making it a crossroads of culture. The city is best known for its many surviving ancient Roman buildings, the most famous of which is its 1st century amphitheatre, which is among the six largest surviving Roman arenas in the world. The star-shaped castle with four bastions is situated on top of the central hill of the old city.