Kirkkosaari ("The Church Island", also known as Köyliönsaari) is one of the oldest places of residence in Satakunta area. Two Iron Age cemeteries are located at the north side of Kirkkosaari.
According the legend Lalli, the pagan chief of Kirkkosaari manor, killed bishop Henry on the ice of lake Köyliönjärvi on January 20, 1156. Although Henry has never been officially canonized, he has been referred to as a saint since as early as 1296 according to a papal document of the time. After this the manor and island was moved as the property of Turku bishop. Since 1746 the manor has been owned by Cedercreutz family and is still in private use. Present buildings are from the 18th and 19th centuries.
The church of Köyliö has been in Kirkkosaari since the Middle Ages. The present wooden church was built in 1752 to the old cemetery site. There are also some remains of the medieval chapel in Kirkkosaari manor garden.
The Royal Palace was built in the first half of the 19th century as the Norwegian residence of King Charles III, who also reigned as king of Sweden and otherwise resided there, and is the official residence of the present Norwegian monarch. The crown prince resides at Skaugum in Asker west of Oslo. The palace has 173 rooms.
Until the completion of the Royal Palace, Norwegian royalty resided in Paleet, the magnificent town house in Christiania that the wealthy merchant Bernt Anker bequeathed to the State in 1805 to be used as a royal residence. During the last years of the union with Denmark it was used by the viceroys of Norway, and in 1814 by the first king of independent Norway, Christian Frederick.