Inside this 15th-century palazzo, today a branch of the National Museum of Rome, is one of Rome’s most charming museums. It’s rarely crowded yet houses some of Rome’s most famous private and public collections of art. The pieces here are not great in number, but they are individually superb; much of the art was once part of the famed Boncompagni Ludovisi Collection, created by Cardinal Ludovico Ludovisi (1595–1632) and sold at auction in 1901.

Among the highlights is the “Ludovisi Ares” ★★, a handsome 2nd-century copy of a late-4th-century b.c. Greek statue of Mars (Ares to the Greeks). Equally renowned is the “Ludovisi Gaul” ★, a marble depiction of a Gaulish warrior plunging a sword into his chest, looking backward defiantly as he supports a dying woman with his left arm—a 2nd-century Roman copy of a 3rd-century b.c. Hellenistic original. Worth a look, is the “Ludovisi Throne,” a sculpted block of white marble, thought to date from the 5th century b.c., depicting Aphrodite rising from the sea. Elsewhere the “Juno Ludovisi” is a massive, 1st-century marble head of the goddess Juno.