The Naantali Church was originally part of the Catholic Convent of St. Bridget. The convent was built between years 1443 and 1462 and church probably later in the end of 15th century. Nowadays the church is the only remaining building of the convent, which was closed during Reformation in 1540s. Naantali Church is damaged several times by fire and the present interior is mostly from the modern times except the pulpit (1622) and artefacts. There are lot of medieval items in church, for example crucifix from the monastery, wooden statues and magnificent altarpiece.
The church is situated in the old town of Naantali, which is mostly built in the 18th and 19th centuries. Finnish National Board of Antiquities has named the church and old town area as national built heritage.
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.