Rychmburk castle was built in the 13th century and belonged to Tas of Rychmburk. One of its owners was Smil Flaška of Pardubice and Rychmburk in the 15th century. In 1425, the castle was seized by Hussites, in the 1st half of the 16th century Jindřich Šťastný of Valdštejn had it turned into a Late Gothic palace, afterwards Kinský had it renovated in the Baroque style in 1793 - 1798.
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.