 The Château d'Angers, built on a schist promontory, dominates the river Maine and the old town.Its site has been occupied since antiquity; the castle itself was built between 1230 and 1240 by Louis IX of France.The massive walls are about one kilometer long and punctuated by 17 towers; they were built with horizontal slices of tuff and schist, giving it strength and an original striped look.