The first fort in Isein was built by bishop Atto of Freising in 784-811 AD. The current Burgrain castle dates from 1200s, when the lords of Burgrain built a four-winged building with keep and moat. The extensive additions and renovation was made in the 15th century by bishop Nicodemus.
After the secularization in 1804 Burgrain castle has been in possession of several owners. In 1906 it was converted into a home for blinds. Since 1919 it has been a private residence.
The castle church dates from 1719 and is richly decorated with rococo plasterwork.
See Burgrain from the Air
https://www.youtube.com/watch?v=EfFImys6EGw
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.