This LEGO model is a working windmill, and was used since the 9th century all the way until recent times. This model is based on one you could have seen in medieval times, and would make a great addition to a medieval village. What's more, it works! If it is placed anywhere with a strong wind, the sails will swing round, turning gears and spinning a big central post, just like a real medieval windmill. This model has one minifigure, the miller. I built this because LEGO hasn't done any medieval windmills, so it would make a great first as a LEGO set.
Here is a video so that you can see the windmill working in all its glory: