The Castle of Fadrell is located in the municipality of Castellón de la Plana. It is a castle of Muslim origin, built between the 11th and 13th centuries.
The castle, with an irregular shape, consisted of four enclosures that adapted to the terrain in a stepped manner. In the upper enclosure is the Alcazaba with three semicircular towers, along with remains of walls and cisterns.
The intermediate enclosure, Albacar, which contains the former, has three more towers and houses the Hermitage of La Magdalena.
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.