La Hougue des Geonnais is a passage chamber from the Neolithic age. It is today largely ruined by quarrying prior to the initial excavation in 1929. There is no capstone anymore. At that time the chamber was found to have a paving of pebbles and a large quantity of pottery fragments were disguarded in the spoil heaps. Excavation between 1985 & 1990 revealed a chamber that was probably constructed in two phases. A D shaped chamber being built first and then later extended to its current form. In 1990 some of the main chamber's missing uprights were replaced by dated, modern grantite blocks. A vast number of finds included pottery, flint scrapers, arrowheads and broken querns.
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.