2 July-6 Sept. The national museum of Castel S. Angelo is open on summer evenings from 20.30-01.00 until 6 September, with free guided tours each night, as part of the fifth annual Notti d'Estate initiative.

All tours include areas usually closed to the public such as the Passetto di Borgo, an 800m-long escape passage linking the former papal fortress to the Vatican; prisons used from Renaissance times up to the 19th century; while those curious to know what a 16th-century pope’s bathroom looked like can check out the Stufetta di Clement VII.

In addition to guided tours there are numerous classical and jazz concerts, an exhibition of photojournalism, and a tribute to Dante on the 750th anniversary of his birth. There is also a bar and restaurant with panoramic views of the capital.

Tickets cost €10, children under 10 go free, and the ticket office is open until midnight. Booking tours is advised, tel. 0688522480 (Mon-Fri 10.00-18.00, Sat-Sun 15.00-18.00) or see website.

Full details and programme available from 1 July.