The Vikings had a stronghold at Aggersborg surrounded by an enormous rampart. Towering to the north of the rampart there is a church of Aggersborg, probably erected during the 12th century. An interesting illuminated inscription of runes can be seen on the walls of the nave and the northern chancel wall. The altarpiece dates back to 1598, but it wasn't placed in Aggersborg until 1934. The previous altarpiece can be seen on the northern wall of the nave. It pictures the founding of The Lord's Supper. There used to be family burial places behind the beautiful lattice.
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.