Joshua 8:24, 28-29

When Israel had finished killing all the inhabitants of Ai in the open wilderness where they pursued them, and all of them to the very last had fallen by the edge of the sword, all Israel returned to Ai and struck it down with the edge of the sword.

So Joshua burned Ai and made it forever a heap of ruins, as it is to this day. And he hanged the king of Ai on a tree until evening. And at sunset Joshua commanded, and they took his body down from the tree and threw it at the entrance of the gate of the city and raised over it a great heap of stones, which stands there to this day.