The Former Cathedral of Baeza was the cathedral episcopal see of the Roman Catholic Diocese of Baeza, which has a Visigothic period, was suppressed after some time under Moorish rule and was shortly restored after the Reconquista under the Kingdom of Castile in the thirteenth century, but suppressed for good, never again to regain (co-)cathedral status.
The site, like the land, alternated between mosque and church during 12th and 13th centuries. The apse still maintains Gothic tracery, but in the 16th-century a major reconstruction by Andrés de Vandelvira in Renaissance-style created the present church. The construction of the cathedral finally ended in 1593, shortly after the death of Andrés de Vandelvira.
The church forms part of a UNESCO World Heritage Site with other monuments in Baeza and in the nearby city of Úbeda.
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.