The Great Wierum Mill is a relatively modern polder mill. It was built in the early part of the 20th century, to an American design called the ’Hercules Wind Engine’. The main benefit of the American mill design is that the mill heads automatically adjust to the direction and strength of the wind, negating the need for a miller. Despite this benefit, the mills quickly fell out of favour, and there are only 13 major, and 40 smaller mills of this type still in service in the Friesland region today.