Perched on the Vomero, this massive castle is almost the size of a small town. Built by the Angevins in the 14th century to dominate the port and the old city, it was remodeled by the Spanish in 1537. The parapets, configured in the form of a six-pointed star, provide fabulous views. The whole bay lies on one side; on another, the city spreads out like a map, its every dome and turret clearly visible; and to the east, is slumbering Vesuvius. Once a major military outpost, the castle these days hosts occasional cultural events. Its prison, the Carcere alto di Castel Sant'Elmo, is the site of the Museo del Novecento Napoli, which traces Naples's 20th-century artistic output, from the futurist period through the 1980s.