Montemolín was inhabited long before our era and received the influence of Lusitanians, Beturians, Celts and the Turduli. During the Arab domination, it was also an important enclave strategically located on the border between Andalusia and Extremadura, with a powerful fortress for defense.
Although there is no record of the beginning of the fortress's construction, it may have been erected around the 12th century. The earliest known information about the fortress dates back to the year 1246 when the castle was reconquered and handed over to the Military Order of Santiago.
The walls of the fortified enclosure cover a significant length, surrounding the hill's summit that dominates the town and offers a clear view over long distances. These walls are made of rammed earth with attached prismatic towers that punctuate the perimeter. The shape is similar to a rectangle about 130 meters long and 50 meters wide, adapted to the natural defensive terrain. The foundations are sometimes made of masonry. In the southeastern flank, the remains of a barbican to protect the main gate are preserved, along with two attached towers, which were typical features of Arab fortresses. The entrance arch, made of brick and over three meters thick, is framed between two octagonal towers, projecting outward and chamfered or octagonal in profile, following a design tradition borrowed from Roman and Byzantine constructions. From the main enclosure, only remnants of seven solid corner towers remain, two of which are covered, and the other five are freestanding. There are two major towers: the Miramontes Tower and the Homage Tower.
During the possession of the castle by the Order of Santiago, very few maintenance and restoration works were carried out.
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.