Visby grew rich in the 12th and 13th centuries as a hub of Baltic trade, first for Gotland’s own merchant-farmers and then for the German traders who made it an early member of the Hanseatic League. The ring wall, begun in the late 13th century, still runs about 3.4 km around the old town, with dozens of its towers intact.
Inside the wall stand the roofless ruins of around a dozen medieval churches, the intact Visby Cathedral (St Mary’s, consecrated 1225) and stone warehouses built for merchants. In 1361 the Danish king Valdemar Atterdag crushed a Gotland peasant army outside the walls and took the town; mass graves from the battle were excavated at Korsbetningen in the early 20th century.
Visby’s decline after the 14th century preserved it: little was rebuilt, and in 1995 the Hanseatic town was inscribed on the UNESCO World Heritage List. Gotlands Museum holds finds including the Spillings hoard, the largest Viking-age silver hoard ever found.