The 18th-century facade of this palazzo on Via del Corso is only a small part of a bona fide patrician palace, still home to a princely family that rents out many of its 1,000 rooms. Visit the remarkably well preserved Galleria Doria Pamphilj, a picture gallery that gives you a sense of the sumptuous surroundings of a Roman noble family and how art was once put on display: numbered paintings (the museum catalog, available from the bookshop, comes in handy) are packed onto every available wall space. Pride of place is given to the famous (and pitiless) portrait of the 17th-century Pamphilj pope Innocent X by Diego Velázquez (1599-1660), but don't overlook Caravaggio's poignant Rest on the Flight into Egypt. The audio guide is by the current Doria Pamphilj prince himself and gives a fascinating personal history of the palace. COST: Galleria Doria Pamphilj EUR7.30, includes audio guide.