On the Free Sunday, the sites that are open and free for everyone are: Colosseum / Roman Forum / Palatine Hill. The Borghese Gallery (booking required) Baths of Caracalla. Castel Sant'Angelo. Ostia Antica. National Rome Museum (Palazzo Massimo, Palazzo Altemps, Crypta Balbi, Diocletian Baths) Villa Giulia (Etruscan museum) More items...