The Gvozdansko Castle was probably built in the second half of the 15th century, due to mining rights of Croatian Zrinski noble family. The castle was first mentioned in 1488. Nikola III Zrinski and his son Nikola Šubić Zrinski frequently came to Gvozdansko in order to inspect the mines and the mint.
The Turks attempted to conquer the Gvozdansko Castle on several occasions. Three major attempts were made in 1561 by Malkoč-beg, in 1574 by Ferhad-beg, and in 1576 by Kapidži-pasha. The final siege by Ferhat-paša Sokolović with 10,000 soldiers, which was fought from 3 October 1577 to 13 January 1578, was much better prepared. That Siege of Gvozdansko ended with an Ottoman victory, after long and bloody siege. Ottomans managed to break into castle only after last defenders froze to death in harsh winter, having no wood or anything else to light the fire, on 13 January 1578.
Ottoman rule in Gvozansko lasted until 1718. Ottoman commander was stunned by the brave Croatian defenders, after witnessing frozen bodies of defenders still holding their muskets on combat positions in the ruined castle.
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.