A good duplex for sale in Detroit is around $20,000 now.
If it's recently empty, it's $5,000 plus back taxes.
If it's been empty for more than a couple weeks, it has already been stripped and burned once or twice and the lot has little value, plus back taxes.
The policy of the Detroit Fire Department to avoid injuries is to allow houses to burn to the ground, then bulldoze them.
The problem with living in most of Detroit is that as soon aa you leave the house to go to work or shopping, your neighbors will see you leave and attempt to break into your house. Fences, razor wire and padlocks help, but in the end it's a losing battle.
Toledo, Ohio is in worse shape than Detroit. When I was there 40 years ago, it was literally a moonscape - just house foundations visible for miles. Not sure if they rebuilt it or not.