Joshua 8:28-31

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. Then Joshua built an altar to the LORD, the God of Israel, on Mount Ebal, just as Moses the servant of the LORD had commanded the sons of Israel, as it is written in the Book of the Law of Moses, an altar of uncut stones on which no one has wielded an iron tool; and they offered on it burnt offerings to the LORD, and sacrificed peace offerings.