What is "bulverket"

The Bulverket is the remnants of a large wooden fortification or bulwark at Lake Tingstäde on the island of Gotland, Sweden. When built, it consisted of a platform with houses surrounded by a double palisade with the entire construction around in diameter.

According to a 1989 archeological survey, the structure was built in the 1130s and may have been used for less than a century. Although its original purpose is unknown, theories suggest it was either used as a shelter during the turbulent times on Gotland at the end of the Viking Age or that it was the site of a last stand.

Among the archeological finds at the Bulverket are the remains of three boats. One of these served as a model for the reconstruction of a Viking boat, the Krampmacken, in 1980. The Krampmacken has subsequently made several journeys following old Viking waterways through Eastern Europe.