Château de Châteaudun was built between the 12th and 16th centuries. The Count of Blois Thibaut V had the keep built around 1170. The Sainte-Chapelle was built between 1451 and 1493. The choir and the high chapel were built between 1451 and 1454, with the nave and the oratory between 1460 and 1464. Jehan de Dunois, the bâtard d'Orléans (Bastard of Orléans), built the west wing (the "aile Dunois") between 1459 and 1468. The bell tower was erected in 1493.
François I of Orléans-Longueville began construction of the north wing between 1469 and 1491. The upper floors were added by François II d'Orléans-Longueville and his descendants during the first quarter of the 16th century.
Today the castle includes a keep, a chapel (Sainte-Chapelle), the Dunois wing and the Longueville wing. Château de Châteaudun overlooks the Loir river. Perched on a limestone outcrop, it shows its origins as a 12th century fortress. Converted during the Renaissance into a comfortable residence, the main body of the building is roofed in the gothic style. It still has, notably, a finely carved staircase from this period. Renovated since the 1930s, the castle has been classed as a historic monument since 1918.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.