The church of Renko was built in the end of 15th century or at the beginning of 16th century. It was consecrated to St. Jacob as well as the Santiago de Compostela Cathedral in Spain. This is why Renko church was a popular pilgrimage destination before Reformation.
Church has an octagonal exterior, which is quite unique in Finnish post-medieval architecture (it's the only one existing octagonal church in Finland).
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.