Episcopal complex of patriach Callixto, Archaeological site in Cividale del Friuli, Italy.

The episcopal complex of Patriarch Callixtus in Cividale del Friuli comprised a basilica, the Baptistery of St John the Baptist and the patriarchal palace. It was the main religious complex of the capital of the Duchy of Friuli. Only scant traces of the buildings survive: the baptistery remains were unearthed in the early 20th century beneath the present cathedral, and the palace remains lie beneath the Palladian Palazzo dei Provveditori veneti, now the National Archaeological Museum.

The complex was built in the time of Patriarch Callixtus, who in 737 moved the episcopal seat from Cormons to Cividale. It comprised the basilica, the Baptistery of St John the Baptist and the patriarchal palace. Excavations have returned few architectural traces but some of the finest Lombard sculptures, among them the baptismal font of Patriarch Callixtus and the Altar of Duke Rachis.

The complex displays two remarkable works from the Lombard period: the Tegurium, an octagonal baptismal font cover, and the Altar of Ratchis with biblical scenes. These objects show the religious craftsmanship of an early era and visitors can view them in the museum today.

The original site of the complex lies beneath the modern cathedral and is not directly accessible to visitors. Key artifacts and religious objects can be viewed in the Christian Museum and the Cathedral Treasury, both reachable through the Via Monastero Maggiore.

The Altar of Ratchis features marble slabs carved with intricate decorative details and set with gemstones that depict Christ, the Virgin Mary, and the Magi. These detailed carvings rank among the rarest surviving examples of Lombard artistry and can be seen in the museum today.