The ruined town of Baelo Claudia is one of Andalucía's most important Roman archaeological sites. These majestic beachside ruins – with views across to Morocco – include the substantial remains of a theatre, a paved forum, thermal baths, a market and the columns of a basilica, and the workshops that turned out the products that made Baelo Claudia famous in the Roman world: salted fish and garum (spicy seasoning made from leftover fish parts). There's a good museum.
Baelo Claudia particularly flourished during the reign of Emperor Claudius (41–54 CE), but it declined in the 2nd century and was gradually abandoned after a 3rd-century earthquake. Live musical performances occasionally happen on July and August evenings.