This imposing structure keeps vigil on the valley and the ancient route along the river Fullone. The Cathedral Church - the most important place of worship in the Diocese - towers majestically over the evocative structure of the Bishop's residence, originally the residence-fortress of Guiscard. It was erected on the ruins of a temple to Poseidon and traces the Norman's progressive affirmation in these lands. Military ascent was accompanied by prestige, inspiring Duke Robert not only to construct magnificent places of worship, but also to obtain the transfer of the Diocese from Malvito, in around 1080. The new episcopal church was created under the best of auspices: it appears to have been dedicated to St. Nicholas of Mira in around 1087, the year in which the Saint's relics were moved to Bari, in the presence of Godoino, “Argentanae Urbis Archiepiscopo”, as certified by documents from the time, who carried part of the relics with him. During the early 18th century its austere Romanesque physiognomy was tempered by Baroque renovations, with the exception of the old bell tower, which collapsed during renovation works in the 1930s, revealing the superb beauty of the underlying Norman Crypt.