Christiansfjel Fortress was initially established by Count Wedel-Jarlsberg in 1683 as Hammersberg Skanse. A tower with a cellar powder magazine was among the first buildings at this Norwegian fortress. During Christian V's 1685 visit to Norway he visited Hammersberg skanse on June 14th. Recognizing its important location on the Swedish border, he renamed the fortress Christiansfjell and directed continued improvements. An extensive report of the visit includes illustrations of the fortress at that time.
After the Great Northern War some of the smaller border forts were determined to be more expensive than their utility justified and they were closed. On July 13, 1742 Christiansfjell Fortress was closed and the materials were moved to Kongsvinger Fortress.
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.