Star-shaped Castel Sant'Elmo was originally a church dedicated to St Erasmus. Some 400 years later, in 1349, Robert of Anjou turned it into a castle before Spanish viceroy Don Pedro de Toledo had it further fortified in 1538. Used as a military prison until the 1970s, it's now famed for its jaw-dropping panorama, which takes in much of the city, its bay, islands and beyond. It's also known for its Museo del Novecento, dedicated to 20th-century Neapolitan art.
The museum's collection of paintings, sculpture and installations documents major influences in the local art scene, including Futurism and the Nuclear Art movement. Standout works include Eugenio Viti's sensual La schiena (The Back) in Room 7, Raffaele Lippi's unnerving Le quattro giornate di Napoli (The Four Days of Naples) in Room 9, and Giuseppe Desiato's magnetic photograph Monumento in Room 18. In Room 17, Salvatore Cotugno's untitled sculpture of a bound, wrapped, muted figure strangely recalls Giuseppe Sanmartino's Cristo velato (Veiled Christ) in the Cappella Sansevero.