I've got a chimney in my 50's-era house that doesn't do anything. It's a regular brick and mortar chimney but it used to be used to vent the old oil heater (it's been converted to natural gas since). ...
In my garage I have a nearly useless room that's 6'x10' but has this ... strange shelf of sorts in there. When I went to bust up the drywall to see whats behind it I found out it's been there since ...