The imposing 13th century castle dominates the town from its proud position at the summit. It was constructed by Pope Nicolo III Orsini in 1277 around an existing tower, and was initially used as his summer residence. It has passed through many hands as power shifted through history and was more recently used as a prison until 1989. Today visitors can visit the chapel, towers and weapons room and are rewarded with breathtaking views across the Tiber Valley and Monte Cimino Park.