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:Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.