The patron saint of Castellaro is Saint Peter in Chains, celebrated on 1 August. The parish church dedicated to him was built in the Baroque style between 1619 and 1634, to a design by the architect Vincenzo Martino, precisely where the old castle once stood, destroyed in 1341, of which only the remains of a semicircular defensive tower and traces of the walls and old entrance gate survive today. Among the sacred objects preserved inside are two crucifixes, one attributed to the Genoese sculptor Anton Maria Maragliano, and a wooden group by the same author depicting Saint Peter freed from prison.
A short distance from the town also stands the sanctuary of Nostra Signora di Lampedusa, built between 1602 and 1619, reached along a road lined with fifteen small chapels depicting the mysteries of the Way of the Cross: the small painting of the Virgin Mary on the high altar comes precisely from the island of Lampedusa. The sanctuary was later the scene of a partial roof collapse, which in the municipality of Castellaro alone claimed 38 victims.
