The site on which Castelgrande stands is rich in history and archaeological findings unearthed during excavations in 1984-1985 confirm that the site was inhabited as far back as the Neolithic period (5500-5000 B.C.) and though to Roman times. Excavation in 1967 brought to light evidence of the first fortification which dates from the 4th century A. C. Documents dating from the 6th century also mention the existence of this first defensive construction.

Castelgrande includes a museum with an archaeological and an artistic section.