Joshua 8:24, 28-29

When Israel had finished killing all the inhabitants of Ai in the field in the wilderness where they pursued them, and they had all fallen by the edge of the sword until they were destroyed, then all Israel returned to Ai and struck it with the edge of the sword.

So Joshua burned Ai and made it a rubbish heap forever, a desolation until this day. He hanged [the body of] the king of Ai on a tree [leaving it there] until evening; at sunset Joshua gave a command and they took the body down from the tree and dumped it at the entrance of the city gate, and piled a great heap of stones over it that stands to this day.