This enormous complex is the best preserved of the ancient bathhouses, which occupied a 50-acre (20.25-hectare) site. The baths were built between 212 and 216 AD by the emperor Marcus Aurelius Antoninus (188–217AD), otherwise known as Caracalla and infamous for killing his own brother. They were in operation for over 300 years and could accommodate over 1600 people. The ruins are impressive in terms of their size and their remaining detail.
Via delle Terme di Caracalla, 52
Open daily 9am-6.30pm (Mondays 9am-2pm). Full price: €8.