The Literal Commandment
Then you shall gather all its booty into the middle of its open square and burn the city and all its booty with fire as a whole burnt offering to the LORD your God; and it shall be a ruin forever. It shall never be rebuilt. (Deuteronomy 13:16)
The literal commandment is that we should burn a city that has turned to idol worship and all its "booty" (things of value).