There has been a wooden church in Källa since the 11th century. After it was destroyed by fire, and with increasing attacks from Baltic invaders, a new church of stone - with the aspect of a fortress - was constructed in stages was built in the 13th century. The two-storied construction, dedicated to St. Olav, was very unusual and made for defensive purposes.
The Källa Church fell into disrepair when a new church was built here in the nineteenth century, but has now been taken into the care of the National Heritage Board and is a major tourist attraction. The most valuable of the old Källa Kyrka's furnishings, including the 15th-century triptych carving and the pulpit from 1600, were moved to the new church.
In the churchyard many of the huge old flat gravestones date from the 1600's and 1700's. Older graves have been discovered from the 11th and 12th centuries.
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.