Silte Church dates from from the 13th century. During restorative work carried out in 1971-72, the remains of a stave church was however found under the floor of the presently visible church, pre-dating the present church with around one hundred years. The oldest part of the now visible stone church is the choir, dating from the middle of the century and in an early Gothic style. The nave is only slightly later, and apparently by the same workshop, while the tower seems to have been added at the end of the century.
The church is an almost unaltered medieval church. Unusually, even the window openings are original. These, as well as the portals, are decorated with stone dressings in alternating colours. The southern portal is also decorated with carved ornaments in Norse style. One of the choir windows contains some original stained glass window panes, dating from the time of the church's construction. Inside, the church is decorated with frescos from four different periods. The earliest date from the time of the church's construction, and are purely ornamental. On the western wall of the nave, a number of frescos from circa 1300 depict several saints. Next to these is a fresco depicting scenes from the Passion of Christ; these date from the middle of the 15th century. A final set of frescos, dated 1495, adorn the souther wall of the nave.
The church has two particularly noteworthy furnishings: the altarpiece and the baptismal font. The altarpiece is unique in its style on Gotland. Its outer wings are painted, and depict St. Michael, Mary and, on the back, the annunciation. These painting date from circa 1500. The central panel, by contrast, is decorated with wooden sculptures depicting the final judgement, and date from the 13th century. The baptismal font dates from the late 12th century and is thus older than the stone church. It was made by Master Sigraf, and is richly sculptured. Most other furnishings such as pews date from 1902, when a renovation was carried out. The pulpit is however from the middle of the 18th century.References:
First record of Kastelholma (or Kastelholm) castle is from the year 1388 in the contract of Queen Margaret I of Denmark, where a large portion of the inheritance of Bo Jonsson Grip was given to the queen. The heyday of the castle was in the 15th and 16th centuries when it was administrated by Danish and Swedish kings and stewards of the realms. Kastelhoma was expanded and enhanced several times.
In the end of 16th century castle was owned by the previous queen Catherine Jagellon (Stenbock), an enemy of the King of Sweden Eric XIV. King Eric conquered Kastelholma in 1599 and all defending officers were taken to Turku and executed. The castle was damaged under the siege and it took 30 years to renovate it.
In 1634 Åland was joined with the County of Åbo and Björneborg and Kastelholma lost its administrative status.