According the legend the first church in Selaön island was built by St. Olaf (Olaf II of Norway) in early 1000s. The current Ytterselö Church dates however from the 1100s. In the late Middle Ages it was changed as a square form hall church with vaults. The funeral chapel of Soop på Mälsåker family was added in 1650. The new choir was completed in 1728.
The beautifully carved triptych dates from c. 1500 and is made in Antwerpen. The crucifix was also made around 1500 and the pulpit around 1600. There is also an unusual tomb in the churchyard; The grave of Hans Åkesson Soop has four pillars and there is stone relief of Soop and his wife.
References: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.