The Abbey of San Michele is a Benedictine Abbey located at the foot of Monte Vulture, on the eastern flank of the Lago di Monticchio Piccolo.
The abbey was founded in the 10th century at the site of grottoes carved into a rock cliff. There is evidence of worship at the site from the 3rd to 4th century of the modern era. Veneration of St Michael Archangel was developed by the Italian-Greek monks at the site, who were then replaced by Benedictines, who erected the abbey, then abandoned it in 1456. it was occupied by the Capuchin friars. An 18th-century church was built at the site near the rock-cut chapel of San Michele.
The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.