The town of Cástulo had been inhabited since the 3rd millennium B.C. It was the capital of the Oretani tribe of Iberians and played a key role in the wars between Rome and Carthage.

Its importance in the ancient world can be explained by its closeness to the rich mines of the Sierra Morena mountains and its strategic location between the valley of the Guadalquivir River and the central plateau. Its greatest splendour was during the Iberian period, the years of Carthaginian influence (the noble Imilce, who married the legendary Carthaginian general Hannibal came from Cástulo) and the Roman period.
At its height, it extended over 40 hectares, making it one of the biggest towns in pre-Roman Hispania. Among the most important buildings and excavations on the site are the theatre, the amphitheatre and a temple dedicated to the imperial cult, dating to the Roman period; there are also fragments of the walls and the sewage network, as well as a number of necropolises and Iberian tombs.