Ekornavallen is one of the richest prehistoric sites in Sweden. The earliest burials were made in the Neolithic period, 3000 BC. The 20 meters wide and two meters high burial mound is dated to Bronze Age (1800-500 BC). There are also lot of different kind of settings (like standing stones and stone circles) from the Iron Ages built between 0-500 AD.
The largest, and best known, of the Neolithic passage graves at Ekornavallen is one called the Girommen which according to early writers means the giant oven. It consists of sandstone slabs, but the mound which once covered the grave is entirely gone. Between the lower passage and the chamber proper lies a very large and thick slab, the "Key stone", resting on the passage stones. The grave was restored in the 1940s when a fragment of a chisel, some amber slivers and some ornate potsherds were found.
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.