The 12th century fortified church of Santa María de Ujué stands on the highest point of the town. It is a fine example of Romanesque architecture, with Gothic additions.
The church originates back to the 9th century when Iñigo Arista ordered a temple to be built next to the fortress that this king ordered to be built. This first pre-Romanesque church was demolished to erect a new Romanesque building in the 12th century under the auspices of King Sancho Ramírez. In the 14th century, Charles II ordered part of the Romanesque naves to be demolished in order to build a single Gothic building. The choir, the undertowers, the crenellated towers and the façades were also built, as well as the church was surrounded by promenades and walls. All of this gave the complex the appearance of a fortress that it still has today. Interred in the church is the heart of Charles II of Navarre.
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.