St. Nicholas' Church stands besides one of Germany's oldest manmade waterways, the Frischen Grube, and was dedicated as the church for sailors and fishermen. The 37m high nave is almost the height of the Marienkirche in Lübeck. The protruding northern and southern vestibules that resemble the arms of a transept are also a particular feature of the church. The lavishly adorned southern gable takes a special place in art of brick construction due to its wealth of glazed figured bricks. From St. Nikolai's medieval interior decoration survives a late-thirteenthcentury granite baptismal font and a maritime altarpiece made in the early nineteenthcentury, but the church's interior is chiefly characterized by completely preserved baroque furnishings.
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.