While we were living in The Netherlands we saw a lot of windmills.  They have a lot more “new” windmills than “old”, but it’s the old ones that are so cool. Most of the old style windmills that I came across were open for tours.  If you get the chance I definitely recommend you check it out, there is so much to learn.  Why do they have so many windmills? Because they use them to pump water out of low lands.  It’s actually they use a paddle wheel which limits how much elevation change you can get… which is why their are so many.  Why do the all have that 360 degree balcony?  So you can rotate into the wind no matter which way it’s blowing and, critically support the back bracing.  How does it rotate into the wind?  With something that looks like the helm / steering wheel on a ship.  What’s inside?  All kinds of stuff – you should really go on the tour!!