The two windmills are the Doesmolen (in front) and the Kalkmolen (in the back). They work in conjunction. The Kalkmolen pumps the water up to the first level, so that the Doesmolen can pump the water out. The Doesmolen dates from 1627 and was in service until 1953. The Kalkmolen was built in 1684 and was first located in Leiderdorp, but has been placed here in 2009 to help the Doesmolen. The water level was lowered, so the Doesmolen could not pump anymore. The Kalkmolen went from green to red at that time.