Hadrian's Villa is less a villa than a small city — the private retreat and architectural playground of the Emperor Hadrian, built in the 2nd century AD. The ruins are spectacular: two bath complexes, theatres, a lake with a private island, palaces and colonnaded courtyards spread across a vast parkland. Everything is in an appealing state of decay, green foliage contrasting beautifully with ancient stone and brick. Allow at least two hours.
Villa Adriana
Emperor Hadrian's sprawling 2nd-century retreat and ruins