Hornberg Castle was built in 1216 by the Nobles of Sulz as a satellite castle to their main castle, Sulz Castle. Hornberg Castle was constructed to additionally secure the connecting road through the Steinbachklinge between the imperial cities of Hall and Rothenburg. Shortly after, the Sulz family built Kirchberg Castle on the other side of the Jagst ford, which evolved into Kirchberg Castle and the town of Kirchberg. Together with Sulz Castle, it secured the ford crossing of the Jagst, an important long-distance route at the time. All three castles were Staufen imperial castles.
In the years following the construction of Hornberg Castle, the village of Hornberg developed, serving as a forecourt for the castle, which was solely built as a core castle.
Subsequently, the castle was owned by several proprietors, making it a joint-heritage castle. In 1339, Albrecht of Hohenlohe-Uffenheim acquired the castle and its lordship. In 1360, fortifications were constructed to secure the castle. From 1504, the Crailsheim family appeared as the sole owners and have remained so to this day. In 1525, the castle was partially destroyed in the Peasants' War. In the following decades, it was rebuilt and transformed into a Renaissance castle. In 1588, the zwinger was rebuilt and economic buildings were constructed. In 1599, the west wing was rebuilt. In 1647, the outer castle courtyard was transformed into an expansive castle garden.
In 1944/45, the castle suffered significant roof damage during World War II, which the owners were able to quickly repair after the war.
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.