Rothenthurn ('red tower') castle may have existed since the 11th century. It was an estate of the Counts of Ortenburg and their successors, the Counts of Celje. A castle is documented in 1478, when the area was held by the Meinhardiner House of Gorizia. The present-day Renaissance building with its chapel was erected from the early 16th onwards, it was acquired by Christoph Khevenhüller about 1525 and afterwards in the possession of several local nobles over the centuries. Today the owners run the castle as a lodging establishment.
References: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.