A seven-storey tower mill on the edge of the old town, De Valk is one of the few remaining stone tower windmills in the Netherlands and the only one in Leiden. The lower floors preserve the miller's family home as it was around 1900; the upper floors hold the original grinding gear and you can climb to the top to see the sails turning when there's a wind.
The platform around the cap, halfway up, is open to visitors and gives a fine view across the old town and the polders. Combine with a walk along the Galgewater canal below.