Ardtole was formerly the Parish Church of Ardglass and is dedicated to St Nicholas, the patron saint of sailors. The structure is of a characteristic Anglo-Irish parish church of the Middle Ages. The long narrow church seems largely of 15th century date, with a huge east window and opposed north and south doors, one with a draw-bar hole. In 1791 a cross-decorated slab of the Early Christian period was found, showing that perhaps the site has a longer tradition than the surviving remains would suggest. A souterrain was also found south of the church. The early cross slab, now built into the Roman Catholic church at Chapeltown, and the souterrain, suggest Early Christian activity on the hilltop.
The Church sat halfway between the Anglo-Norman settlers and traders of Ardglass and the native Irish of the surrounding area, but was used by both sets of people until the 15th or 16th century. According to tradition some people from Ardglass found the chieftain of the MacCartans in a drunken sleep and fastened his hair to some briars. He avenged this affront with a massacre of the townsmen gathered together for mass in Ardtole Church. This disaster led to the abandonment of the building as a place of worship for Ardglass, probably in the 16th 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.