The Heidetränk Oppidum near Oberursel is one of Europe"s most important Celtic oppida. The oppidum was surrounded by ramparts which encircled the settlement of opposite sides of a ravine called the Heidetrankthal. This imposing rampart where 10 km long and had six gates. The high point of the settlement was in the late La Tène period, but lost its importance in the mid first century BC. Archaeological finds from the Heidedtrank Oppidium include agricultural implements such as plowshares, hoes, scythe and sickle blades as well as tools and Celtic coins, particularly the so-called 'Nauheim Quinarius', which was probably coined in the oppidum itself.
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.