CaCO3 + heat → CaO + CO2

You find them wide spread across the country. My favourites in Holy Island...they are building a housing development in South Edinburgh called The Kilns with the structures close by.... near Pencaitland....and in Fife giving their name to the village from which a young village girl rowed David Balfour across the Forth as he returned to Edinburgh after his adventures in Kidnapped.

They were very, very common. Turning limestone into quicklime.

This one is on the back road from Edinburgh to Peebles. A much more well preserved kiln is close by.