Kegnæs Church was built in 1615 by John II, Duke of Schleswig-Holstein-Sonderburg. It was built in the style of many local Romanesque style churches. The altarpiece dates from about 1450 and was formerly (like the font and pulpit) situated in the now vanished St. Nicolaj Church in Soenderborg. The figure of Christ is from about 1500 on railing between nave and chancel. Two side figures, the Virgin Mary and the apostle John are from about 1691.
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.