Seili (Själo in Swedish) is a small island in the Archipelago Sea. The island is known for its church and nature, a research institute and a former hospital. The first hospital on Seili was established in the 1620s. Before that there were two farms on the islands belonging to the Crown and thus available when the authorities looked for a suitable island to which the leper hospital at the outskirts of Turku could be moved.
According to a Royal Decree in 1619 by King Gustav Adolf of Sweden, the buildings of the hospital in Turku, with the exception of the chapel, were burned down and the inmates transported to Seili. The Selihospital for lepers was dedicated to St George. The last leper patient died in 1785, and the establishment on Seili became a hospital or a place of confinement for mentally afflicted people until 1962. The hospital was self-sufficient with agriculture, and fishing. The present-day buildings on the island, with the exception of the chapel, date from the 19th and the 20th centuries, and most of them have been built for the mental hospital.
The wooden chapel of Seili was built in as a replacement of the Church of Saint George, the former hospital church which had been transferred to Seili from Turku in the beginning of the 17th century. The museum church has a cross-shaped plan and it is made of pinewood grown in archipelago islands. The original untreated wooden surface can still be seen inside the church and nowadays it is beautifully patinated by passed centuries. The only colourful objects in the otherwise quite barren but impressive interior are the pulpit decorated by C.J. von Holthusen and the modernistic altarpiece The Storm on Lake Genesaret painted by the Finnish artist Helge Stén.
Currently the island hosts the Archipelago Research Institute that is a part of the University of Turku. The island is open to the public in summertime and there are guided tours available. During the summer season, the connecting ferry m/s Östern operates on the Nauvo-Seili-Hanka (Aasla, Rymättylä) route. Therefore, Seili is accessible from both Nauvo and Hanka.
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.