Sign says that the exhibition at the De Adriaan Windmill (Molen de Adriaan) is open in Haarlem, the Netherlands A sign informs visitors that the exhibition is open at the De Adriaan windmill (Molen de Adriaan) in Haarlem.A sign informs visitors that the exhibition is open at the De Adriaan windmill (Molen de Adriaan) in Haarlem.