The Castello Normanno ('Norman Castle'), or alternatively the Castello di Aci, is situated on a rocky outcrop jutting out into the sea. Its precise date of construction is uncertain, but it was important to the development of its region during the Middle Ages. During the War of the Sicilian Vespers, it was subject to Roger of Lauria. It was besieged more than once, and was briefly controlled by the Spanish. It is currently a museum.
The town of Aci Castello developed around the castle, which was built in 1076 by the Normans upon the foundations of a 7th-century Byzantine fortification. In 1169, Aci Castello started to expand after an eruption of Mount Etna made the towns in its vicinity uninhabitable. The castle later became the property of the Bishops of Catania.
In 1296, Roger of Lauria, admiral of the Aragonese fleet during the War of the Sicilian Vespers, was granted the fief of Aci and its castle as a reward for his faithful service to King Frederick III of Sicily. When relations between the two men soured and di Lauria transferred his loyalties to the Angevins, the castle was besieged and captured by King Frederick and di Lauria stripped of his fiefs. In 1320, the castle and Aci were taken from Roger's descendant, Margaret of Lauria and given to Blasco II de Alagona. Whilst the latter was away defending Palermo from the attacking Angevins, Bertrando di Balzo sacked Aci in his absence.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.