Joshua 8:28-31

So Joshua burned Ai and made it a permanent heap of ruins, a desolate place to this day. He impaled the body of the king of Ai on a pole and left it there until evening. At sunset, Joshua ordered them to take the body from the pole and throw it down at the entrance of the city gate. And they raised a large pile of rocks over it, which remains to this day. Then Joshua built on Mount Ebal an altar to the LORD, the God of Israel, as Moses the servant of the LORD had commanded the Israelites. He built it according to what is written in the Book of the Law of Moses—an altar of uncut stones, on which no iron tool had been used. On it they offered to the LORD burnt offerings and sacrificed fellowship offerings.