Any guesses?

We've been passing these odd buildings since entering Kent. My first guess was some sort of variation of solar panels. What I keep forgetting is just how old this country and these buildings are. No solar panels in the 18th century. Turns out these "Oast Houses" have been a symbol of Kent for centuries. They are towers used for drying hops grown in local fields. The towers are kilns layered with thin floors allowing the heat to move up. The white "cowls" move with the wind and allow the excess heat to escape. New processes and heat sources make these historical oddities but they are still maintained - some now houses. Oast is Kentish for kiln.