Caer y Twr (fort of the pile) is an Iron Age hillfort atop the summit of the Holyhead Mountain in Anglesey, Wales. The hillfort, which is situated among rocky outcrops, is ideally placed for defence and likely served as a watchtower and possibly as a signal tower. Some have speculated that it was built to alert a small fort in the modern town of Holyhead in the case of raiders coming in from the Irish Sea, while others have suggested that it may have been a lighthouse.
The hillfort is now mostly rubble, but its walls can still be made out, including a large stone rampart on the north and east sides which reaches 3 metres at points. The entrance to the fort was through a rocky gully. The footings of a tower were discovered when the site was excavated; its stones are believed to date from the 2nd to the 4th centuries.
Nestled below Caer y Twr is a group of several enclosed huts, named Cytiau Tŷ Mawr (the Holyhead Mountain Hut Circles), that also date from the 3rd to the 4th centuries, some of which still contain the accoutrements of life, such as hearths and shelves.
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.