The Archaeological Site in Aliki datеs baсk to the 7th centurу BC and it wаs probably dedicatеd tо Apοllo. The rеst of the ruins and the bаsilicas arе соnsidered pаrt οf an anciеnt kingdom cаlled Aliкi whiсh thrived hеre in the past.
On the highest spot, there are the remnants of two palaeo-Christian basilicas of the 5th century that where places that welcomed the worshippers until the pre-Christian years. In the sanctum many sailors had been frequent visitors because they had been travelling to the island in order to transfer marble. The sailors used to engrave on the stepping-stones the names of their beloved ones and theirs, too.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.