The archaeological complex of San Giovanni is located on the site of a ruined castle of Norman origin. A symbol of feudal power, the castle was partially destroyed in the 15th century and Bishop Turnfranza used its materials to decorate the cathedral and to build the Basilica of San Giovanni (1532) with the help of the monolithic confraternity. Some of the items were used to decorate the Chapel of the Ocervanza. In May 1589, the congregation of Santa Croce, which was already involved in helping the sick, asked the local university to be able to build a ward to be used as a hospital.