Trevejo Castle origin dates back to before the 12th century when a Muslim fortress stood in its place, serving as the basis for its construction in the 15th century. The original fortress was conquered by Alfonso VII of León, who handed it over to the Order of the Temple. In 1184, by order of King Fernando II of León, it passed into the hands of the Order of St. John of Jerusalem. Two years later, the same monarch decided to give it to the Order of Santiago. Over the course of history, it also came to belong to the Order of Alcántara.
During the French invasion of the peninsula, the castle was destroyed to prevent Spanish guerrillas from taking refuge in it.
Today, the homage tower and a large part of the wall still resist the passage of time. At the foot of the castle, there are a series of anthropomorphic stone tombs, allegedly containing the remains of some of the warrior monks who were initially owners of the castle.
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.