San Nicolás de la Villa is one of the twelve Fernandine churches built in the city after its conquest by King Ferdinand III of Castile (1236), in Gothic-Mudéjar style, although it was completed only in the following centuries, with much renovation added in the meantime. The main portal, in Renaissance style, was added by Hernán Ruiz the Younger in the 16th century. The octagonal tower, with a defensive appearance, was rebuilt during the age of the Catholic Monarchs above an older Islamic minaret.
In the 17th and 18th century, much of the church's elements were modified until it received the current mostly Baroque appearance. The baptistery dates from 1555.
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.