Bouillon Castle was mentioned first in 988, but there has been a castle on the same site for a much longer time. The castle is situated on a rocky spur of land within a sharp bend of the Semois River.
In 1082, Bouillon Castle was inherited by Godfrey of Bouillon, who sold it to Otbert, Bishop of Liège in order to finance the First Crusade. The castle was later fitted for heavy artillery by Vauban, Louis XIV's military architect in the late 17th century.
The castle is entered over three drawbridges. The main courtyard then leads to the ducal palace with its 13th century Salle Godefroy de Bouillon. From there visitors climb up to the top of the 16th century Tour d’Autriche for a breathtaking panorama of the town and river, before they way back via the torture chamber, citerns and dungeons, and past the 65m deep well Shaft.
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.