The history of both towns exemplifies in an ideal way the genesis and development of Hanseatic towns on the southern shores of the Baltic. Wismar and Stralsund are planned towns initiated by their sovereigns as a result of the German colonisation of Slavic territories in the 12th and 13th centuries. When Wismar was first mentioned in a document in 1229, and Stralsund in 1234, we can assume that relatively large settlements already existed.
Wismar was founded at the beginning of the 13th century at a distance of about 1.5 km from the Wendish fishing village of Alt Wismar and only 5 km to the north of the Mecklenburg, the centuries-old centre of the Slavic Obodrites. Also in Stralsund was there a Slavic fishing and ferry village, which maintained the link to the island Rügen, long before the actual town was founded. Its name was probably that used for the town when it was first mentioned in documents: Stralow.
Both towns provided excellent conditions for the founding of a town and its subsequent development. The protected natural harbours directly on the shores of the Baltic and the favourable traffic routes were especially important factors in the development of the towns and an extremely good starting point for the later involvement in long-distance Hanseatic trade.
Soon after being granted cooperation statutes, Stralsund and Wismar began with the construction of solid city walls in order to protect the rapidly developing towns. In Stralsund, parts of the wall were in position as early as 1256. Six sea gates and four or five land gates interrupted the walls and gave access to the town. In 1276, the palisades of the three constituent settlements of Wismar were replaced by a common city wall made of stone, with ramparts and moats, two water gates leading to the harbour and three land gates. A very important addition to the systems of fortifications in Stralsund and Wismar were the ponds, which at the time of the early development of the two towns were dammed up.
In both towns, in the 13th century the ground plan with its streets and squares developed according to Lübeck Law. The beginnings of the large buildings - the churches, monasteries, town halls and the city walls - date back to this time. Wismar had grown to a size which was not to be exceeded until the 19th century, and the same applied to Stralsund by the end of the 13th century.