Aiello Calabro Castle was probably buillt in the Byzantine period in the 9th century against Arabian raids. It was besieged four months by Norman count Robert Guiscard in 1065. He lost two of his nephews in the siege.
The current ruins date mainly from the 15th century. In the 16th century it was one of the most powerful castles in southern Italy. Aiello Calabro castle was destroyed by earthquakes of 1638, 1783 and 1905. Today part of curtain walls and towers remain.
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.