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. It has three radially situated apses and an ambulatory around the central area, surmounted by circular gallery. The circular shape is typical of the early medieval age in Dalmatia. It was built on the Roman forum, and materials from buildings in the latter were used in its construction. Among the fragments which are built into the foundations it is still possible to distinguish the remains of a sacrificial altar on which is written IVNONI AVGUSTE IIOVI AVGUSTO.
The use of the church has varied during its lifetime; during the rule of the Republic of Venice it was a warehouse, as well as during the French occupation and under the Austrians. After the city was annexed to Yugoslavia, it served as an archaeological museum for a short period of time. The building is currently used as the concert venue for the annual International Festival of Medieval Renaissance Music due to the building's interiors and acoustics.References:
First record of Kastelholma (or Kastelholm) castle is from the year 1388 in the contract of Queen Margaret I of Denmark, where a large portion of the inheritance of Bo Jonsson Grip was given to the queen. The heyday of the castle was in the 15th and 16th centuries when it was administrated by Danish and Swedish kings and stewards of the realms. Kastelhoma was expanded and enhanced several times.
In the end of 16th century castle was owned by the previous queen Catherine Jagellon (Stenbock), an enemy of the King of Sweden Eric XIV. King Eric conquered Kastelholma in 1599 and all defending officers were taken to Turku and executed. The castle was damaged under the siege and it took 30 years to renovate it.
In 1634 Åland was joined with the County of Åbo and Björneborg and Kastelholma lost its administrative status.