This gem of a museum houses the best of the Museo Nazionale Romano's formidable collection of classical sculpture. Many pieces come from the celebrated Ludovisi collection, amassed by Cardinal Ludovico Ludovisi in the 17th century. Prize exhibits include the 5th-century Trono Ludovisi (Ludovisi Throne), a carved marble throne depicting Aphrodite being plucked from the sea as a newborn babe. It shares a room with two colossal heads, one of which is the goddess Juno and dates from around 600 BC. The wall frieze (about half of which remains) depicts the 10 plagues of Egypt and the Exodus.

The building's baroque frescoes provide an exquisite decorative backdrop. The walls of the Sala delle Prospettive Dipinte are decorated with landscapes and hunting scenes seen through trompe l'œil windows. These frescoes were painted for Cardinal Altemps, the rich nephew of Pope Pius IV (r 1560–65) who bought the palazzo in the late 16th century. Note that there is sometimes a €3 exhibition supplement.