Theatre of Marcellus

Augustus completed this theatre in 13 BC and dedicated it to his nephew Marcellus, who died young — making it older than the Colosseum, which it directly inspired in design. The two surviving lower tiers of arches show stacked Doric and Ionic orders, a template the Colosseum later expanded. In a remarkably Roman twist, the upper levels were converted into a fortified palace by the Orsini family in the Middle Ages, and apartments are still occupied there today — meaning real residents live inside an Augustan-era theatre.