The place dominated by the Ucero castle has been inhabited since prehistoric times. The castle is built on the site of an ancient Celtiberian castro. The site was first time mentioned in 1157 when Alfonso VII located the village of Sotos the Suso between Uxama and Ucero and there are documents that indicate that the castle already existed in the 13th century. It is estimated that the important hermit of San Juan de Otero, nowadays destroyed, was ubicated near San Bartolomé, which was a Templarian chapel.
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.