Thierstein Castle was built in the early 14th century by Albrecht VI of Wildstein. Later it was moved to the hands of Nuremberg burgraves and the house of Hohenzollern. In 1553, during the Second Margrave War, Thierstein was occupied by Bohemian troops. In 1603 Margrave Georg Friedrich of Brandenburg ordered to abandon the castle and the construction of a new office building outside the village of Thierstein. Nevertheless, the most necessary repairs were still carried out at the Thierstein castle during the Thirty Years' War. The end of the Thierstein castle came in 1725, when it was destroyed by fire.
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.