Joshua burned Ai and made it a permanently uninhabited mound (it remains that way to this very day). ¹ 

But Israel did not burn any of the cities located on mounds, ¹  except for Hazor; ²  it was the only one Joshua burned.

The Lord says, “I will restore the ruined houses of the descendants of Jacob. I will show compassion on their ruined homes. ¹  Every city will be rebuilt on its former ruins. ²  Every fortified dwelling will occupy its traditional site. ³ 

You must gather all of its plunder into the middle of the plaza ¹  and burn the city and all its plunder as a whole burnt offering to the Lord your God. It will be an abandoned ruin ²  forever – it must never be rebuilt again.

Because you did that, I, the Lord, affirm that ¹  a time is coming when I will make Rabbah, the capital city of Ammon, hear the sound of the battle cry. It will become a mound covered with ruins. ²  Its villages will be burned to the ground. ³  Then Israel will take back its land from those who took their land from them. I, the Lord, affirm it! ⁴