The Alcazaba of Antequera was erected in the 14th century to counter the Christian advance from the north, over Roman ruins.
The fortress is rectangular in shape, with two towers. Its keep (Torre del homenaje, 15th century) is considered amongst the largest of Moorish al-Andalus, with the exception of the Comares Tower of the Alhambra. It is surmounted by a Catholic bell tower/chapel (Templete del Papabellotas) added in 1582.
Connected to the former by a line of walls is the Torre Blanca ('white tower').
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.