The castle of S. Martino was founded in the Lombard era on the site of a late Roman stronghold as the center of a system of lookout points located on the surrounding hills: renewed several times, it presents itself as a heterogeneous complex, with the most significant walls referring to the 15th-16th century, when the Brevia road was opened, facilitating access from the Piazza del Duomo. The castle has been an episcopal residence since the 10th century, when the bishop also held the title of count and a temporal power that he retained until 1768. A massive crenellated tower recalls its original military function. Instead, the residential core has a Renaissance style, set around the central courtyard, where the beautiful arches of the Courtyard of Honor open up.
