As part of the National Year , the National Windmills Day is held in May in Holland .
During this great event, as many as 600 mills held their blades positioned in the middle.
The position of the blades has a meaning to be rediscovered in the past when this system was used to report messages to the population living in the nearby villages.
With the ‘ arrival position ‘, ie the one in which the blades stopped before reaching the highest point, the miller warned of a happy event. With the ‘ going position , the one in which they stopped vertically passing through the same point, he felt instead of a bad event.
During the Second World War, the mills’ shovels were used in the event of an alarm to send encrypted messages such as that of imminent raids.
Today in Holland many Windmills are still used as those of Zaanse Schans that still perfectly working are used as sawmills, in the use of crushers, for the production of mustard and for the millstone used to be used for colors and paints . Others have even been rebuilt to revive the customs and culture of the past.
On this day all eight Amsterdam windmills for the occasion will be decorated and open to the public when it is normally possible to visit only two. The old village and the open-air museum in the Zanstreek will also be recreated to the north of the Dutch capital.