Lake fortress
Lake fortress (Ezepils, "lakefort") is a type of fortified settlements mostly built on wooden platforms on lakes of Latvia build during 7th-11th centuries in the lands of Latgalians. All known sites are underwater. The best known one (and the first discovered one of this type) is the reconstructed Āraiši lake fortress (Latvian: Āraišu ezerpils) on the Āraiši Lake.