Østerlars Church is the largest and, possibly, the oldest of the Bornholm island's four round churches. Built in about 1160, it was dedicated to St. Lawrence. It consists of an apse, an oval chancel, a large round nave and has three storeys. There is evidence the church was once fortified, the top storey serving as an open shooting gallery. The fieldstone wall stands on foundations of Bornholm limestone. The double-arched apse bears similarities to that in Lund Cathedral. The round nave has an external diameter of 16 meters. In its centre there is a large round hollow column, six meters wide. An opening, known as the oven, leads into a small room inside the column.
Originally there were small Romanesque windows but these were enlarged after the Reformation. During the 16th century, a number of pillars were added to support the outer wall. The conical roof was replaced in the 17th century. The porch is from 1870. The bell tower stands separately from the church in the churchyard, and the bell tower was the original entrance and gate tower. There are two runestones, one inside the porch (c. 1100) and another outside (c.1070).
The church's central column is decorated with frescos from 1350 showing biblical scenes from the Annunciation through to the Passion, ending with Day of Judgment where Jesus judges mankind. Many of the naked figures are sent to hell, symbolized by a huge dragon. They were probably painted some 140 years after the church was built. The frescos, which had been hidden with limewash since the Reformation, were uncovered in 1882. The pulpit is from 1595. The carved altarpiece is from c. 1600.
Erling Haagensen, co-author of The Templars' Secret Island, believes there is a connection between the round churches of Bornholm and the Knights Templar. He believes there are similarities between the geometrical precision of the churches' locations and those of churches in Rennes-le-Châteauin France. He concludes that Østerlars, and the other round churches, could have been used as supply stores for the crusades.
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.