St. Nicholas Church is a large, cruciform town church set on Place Dalton at the heart of the lower town which clusters below the walls of the citadel. Due to the destruction of the French Revolution, WWI and WWII it is the most significant surviving medieval building in the town.
The church is first mentioned in 1208 as a foundation of the Abbey of Notre-Dame within the citadel, a relationship which existed into the 16th century. About this time, the silting up of one of the channels caused the centre of the town to move southwards, and St Nicholas took over from St Peter as the main town church.
The vaulted roofs in the nave and transepts were installed in the 17th century, but their weight caused the walls to crack, and as part of the rebuilding the nave was widened and lengthened, a response to the doubling in population of the lower town that century.
All the glass was destroyed during the liberation, and has so far been replaced in the lower stories with some splendid 1980s abstract designs.
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.