Joshua 8:28-29
8:28 Joshua burned Ai and made it a permanently uninhabited mound (it remains that way to this very day).
8:29 He hung the king of Ai on a tree, leaving him exposed until evening. At sunset Joshua ordered that his corpse be taken down from the tree. They threw it down at the entrance of the city gate and erected over it a large pile of stones (it remains to this very day).