Originally there were 15 windmills within the old defensive walls of Delft, but only one survives today. This is the Windmill De Roos built in the 16th century on the town ramparts.It ground grain for bakers and barley, oats and corn for farmers. In those days it was a hexagonal wooden post-mill, but in 1679 it was partly demolished and refashioned with a much higher round stone tower.
It needed extensive restoration work between 1988 and 1990, but is now back in full working order.