Borgholm City Museum is housed in a beautiful building dating from the first half of the 19th century. The permanent collections include displays of tools, weapons, domestic objects, clothing and handicrafts created over the centuries. You can see examples of authentic period interiors. The basement contains a collection of archaeological finds from the earliest years of settlement. There is also a collection of model ships, an exhibition on resort era Borgholm and a display on the history of firefighting in the city.
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.