Milengrad was built during the reign of Hungarian–Croatian King Béla IV after the Mongol invasion of 1241–1242. Around 1303, King Charles Robert donated the fortress to the Cseszneky family in compensation for their loss of Ipolyvisk Castle. The counts Cseszneky sold it soon to Ban Mikcs, who, in 1309, ceded the lordship to the Herkffy family. In 1536, by the marriage between Katalin Herkffy and Miklós Patačić, Milengrad became the two families' shared property. In the 17th century, the Herkffy family became extinct, and the Patačićs followed in the 19th century. Due to the constant warfare with the Ottomans, and probably as well to an earthquake, by the late 17th century several walls of Milengrad fell down, and in 1683 it was already mentioned as arx diruta, a castle in ruins.
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.