The Kehlburg castle was built probably in 933 By the bishop Altwin of Brixen at the hillside over Gais. The most important owners later were the noble family Rost zu Aufhofen, which had the castle in possession for nearly three centuries.
After the fire in 1944 where the castle was nearly completely destroyed, the chapel of the holy Erasmus was rebuild so this was used for many years as a much visited pilgrimage. Unfortunately the castle and the chapel is damaged by vandalism.
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.