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:
Ängsö Castle was first named as "Engsev" in a royal charter by king Canute I of Sweden (r. 1167-1196), in which he stated that he had inherited the property after his father Eric IX of Sweden. Until 1272, it was owned by the Riseberga Abbey, and then taken over by Gregers Birgersson.
From 1475 until 1710, it was owned by the Sparre family. The current castle was built as a fortress by riksråd Bengt Fadersson Sparre in the 1480s. In 1522, Ängsö Castle was taken after a siege by king Gustav Vasa, since its owner, Fadersson's son Knut Bengtsson, sided with Christian II of Denmark. However, in 1538 it was given by the king to Bengtsson's daughter Hillevi Knutsdotter, who was married to Arvid Trolle.
In 1710, the castle was taken over by Carl Piper and Christina Piper. Ängsö Castle was owned by the Piper family from 1710 until 1971, and is now owned by the Westmanna foundation. The castle building itself was made into a museum in 1959 and was made a listed building in 1965. It is currently opened to visitors during the summers.
The castle is a cubical building in four stores made by stone and bricks. The lower parts is preserved from the middle ages. It was redecorated and expanded in the 1630s. The 4th storey as well as the roof is from the expansion of Carl Hårleman from 1740-41. It gained its current appearance in the 1740s.