Caer Gybi in Holyhead contains the remains of a small Roman fortlet and naval base, whose atmospheric ruins can today be explored. Although the construction date of Caer Gybi is unknown, it is believed that it was built in the late 3rd or early 4th century. The structure was made up of three defensive walls with circular watch towers at each corner, while the fourth side fronted the sea and may have been a dock for the Roman warships that would have patrolled the area.
It is thought that Caer Gybi was constructed to defend against Irish sea raiders, and as a smaller fortlet was probably an outpost of the larger Roman fort at Segontium. It is believed that the Roman watchtower, which stood on the nearby Holyhead Mountain, served as the lookout post for Caer Gybi.
The Romans abandoned the region in the late 4th century, and by the 6th century the site had been given to Saint Cybi who founded a monastery within the walls. The medieval Church of St Cybi still stands there today.
Today, visitors to Caer Gybi can still view much of the original Roman defences, with walls standing up to 4m in places and at least one original corner 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.