The archaeological remains found near the Águila Castle seem to confirm the presence of a pre-islamic population, maybe from the Roman Age.
Apparently in 914 the inhabitants of the fort looked like emirales troops burned the city of Algeciras ships that supported the revolt on Ibn Umar Hafsun, in any case the construction of the castle had to be early to be this hard hit area by Berber rebellions and Mozarabic.
The castle was restored in 1839 after it was conquered by French army in 1810. It was however badly damaged in the explosion in 1842.
The Águila Castle is the most representative monument in Gaucin, from the fortress you can see stunning views, in a clear day you can even see the North of Africa.
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.