Homburg Castle was built in the early 1170s by the Lords of Hohenberg, who were Würzburg ministeriales. Through inheritance it passed to the Bickenbach family in 1381. In 1469, the community along with the Homburg and the surrounding places was sold to the Prince-Bishopric of Würzburg.
The current appearance dates from the 13th and 15th centuries. Homburg was badly damaged by fire in 1680 and started to decay. Today ruins are open to the public.
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.