On this spot the first wind mill was build in 1619. Build on the city wall, the mill served to produce flour for bread for the citizens of Leiden. The city of Leiden had up to 19 of these mills. One very nearby, on the other side of the Galgewater was owned by the parents of Rembrandt van Rijn, the famous painter. Both sides of the Galgewater were connected by a bridge.
The first mill here was a wooden Standerd Korenmolen which burned down in 1640. The subsequent mills eventually were build of stone and higher (type Stelling Korenmolen). In 1817 barracks were build on this spot, right behind the Morschpoort (nearby city gate). The barracks stayed until 1981, when it was replaced by housing and square.
Since 8 May 1987 a replica of the first wind mill (1619) can be found again on this spot. Also the old drawbridge (Rembrandtbrug) has been rebuild.
More info: http://www.molendeput.nl/ (Dutch)