Molen de Valk is build in 1743. The current mill had two predecessors, the first one being build on this spot in 1611. The mill has four pairs of mullers, producing lots of flour. This mill is the only of 19 remaining old mill.
Currently the mill is a monument and museum, and open to visit and see all floors of the mill inside. It's closed on mondays.
More info: http://molendevalk.leiden.nl/ (multilingual)