The typology of houses, such as the Dielenhaus and the Kemläden, were developed in the 14th century and became a characteristic feature of many Hanseatic towns. Wismar has preserved its medieval harbour basin, whereas the island location of Stralsund has remained unchanged since the 13th century. AuthenticityThe towns contain a large number of authentic historic structures representing the evolution from the Hanseatic period to the Swedish era. Wismar as well as Stralsund have management plans, which are updated regularly. Both municipalities involve local and external experts who encourage consistency and appropriate solutions in building and town-planning practice (Architectural advisory board Stralsund, World Heritage council Stralsund, Architectural advisory board Wismar).