St. Nicholas Church in Altefähr was built of brick in the second half of the 15th century to the site of earlier 13th century chapel. It was painted in 1692 and the tower restored. The next renovation took place in 1737. After the upper third of the tower had collapsed in 1803, the tower was rebuilt. Another extensive renovation of the church took place in 1912-1913. The interior contains valuable wall murals from the 15th century.
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.