The neoclassical church of Askainen was built by the owner of Louhisaari Manor, Governor-general Herman Claes'son Fleming in 1653 as the chapel church of Louhisaari Manor. It’s one of the rare stone churches in Finland built after the Reformation in the 17th century. The belfry was erected in 1772–1779. There is a funeral chapel of the Mannerheim family in the cemetery.
The Askainen noblemen's church is part of the oldest tourist route in Finland, the Seven Churches Tour, together with Raisio, Masku, Nousiainen, Lemu, Merimasku and Naantali. Finnish National Board of Antiquities has named the church and near Louhisaari manor 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.