Cittadella is a medieval walled city founded in the 13th century as a military outpost of Padua. The surrounding wall has been restored and is 1,461 metres in circumference with a diameter of around 450 metres. There are four gates which roughly correspond the points of the compass.
The town was founded in 1220 by the Paduans to counterbalance the fortification of Castelfranco. It was built in successive stages in a polygonal shape on orthogonal axes through the construction of 32 large and small towers, with the formation of a protective moat and with four drawbridges next to the four entrance gates.
Its walls, 14 to 16 metres tall, were built with the 'box masonry': two parallel walls filled with a sturdy core of stones and hot slaked lime totaling a thickness of about 2.10 metres.
The walls today are all intact except for a stretch destroyed in the 16th century during the Cambrai war, and the skilled detail of the construction are still easily visible. It has as many as seven different construction techniques characterized by the alteration of courses in brick and those in river rocks mixed with brick can be recognized.
Among the elements of interest, the Rocca di Porta Bassano still retains the defense apparatus of the keep and entrance gates. The Casa del Capitano (Captain's House) is found inside the Rocca (Fortress). Restoration has uncovered frescoes dating to the period of the Carraresi, Malatesta, Sanseverino and Borromeo families. They hand down an out-and-out historical account of the events that occurred between 1260 and 1600, almost replacing written documents.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.