Jellhaugen is the second largest burial mound in Norway and among the largest in Scandinavia and Northern Europe. It has a diameter of 85 metres and a height of around 9 metres. It's difficult to know exactly how old it is, but another nearby burial site known as the Jellhaugen Mound has been dated to around 1,500 years ago.
A saga tells that the mound is buildt for a king called Jell, however these tales are from more modern times and cannot be trusted. The mound is not completely excavated, only parts of it have been excavated, in 1968 however, it was dug a ditch trough the centre of the mound and the only findings was a cremation grave with burned human bones and a single amber pearl. The grave has been carbon-dated to around 426-598AD, the end of the age of migration. Traces of a early grave robbing was dated to around 692-896AD.
In 2018, using high-resolution ground-penetrating radar, archaeologists have found an ancient Viking cemetery, complete with what appears to be a well-preserved ship burial. A popular mode of interment among the Norse Vikings, ship burials consisting of a longboat covered by a mound were reserved for important personages, such as chieftains.
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.