Polders are lands separated from the sea by dams in order to control water levels artificially. In the Netherlands, the Dutch built dams starting in the Middle Ages to protect agricultural lands from floods and create more arable land. Initially, dams were used for protection, then windmills with pumps were used to drain water. Some famous Dutch windmills include Kinderdijk, which explains how the Dutch avoided floods, and Schiedam windmills, some of the largest in the world formerly used for grain grinding and gin production. The Beemster Polder is a UNESCO World Heritage Site where 42 windmills were built between 1607-1612 to drain the land, and some original aristocratic