The St. Nicholas Cathedral or just Feldkirch Cathedral is part of the old town and is the largest Gothic church in Vorarlberg. With the founding of the diocese of Feldkirch parish church it became a cathedral on 12 August of 1968.
In the city fires of 1348, 1396 and 1460 the building of the original church was badly affected. In 1478 the church built under the plans of architect Hans Sturm added a new late Gothic nave equipped with a double deck. The present choir was built around 1520. The church is further complemented by the vestry and a baptistery.
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.