Barracks Road Tunnel
First of all, this isn't an abandoned thing but just something that kinda fits in the urban exploration category. Second, while it is a tunnel it's not anything that people were meant to go in like the Blue Ridge Tunnel. It was made for a creek to go underneath a shopping center.
Above is a clip I made for instagram. It kinda shows what it's like. If you've ever been through the tunnels on the Rivanna Trail then you'll know what it's like. These are the same concrete pipes just much longer. This one is a quarter of a mile and goes from one end of the Barracks Road Shopping Center to the other. This was the first tunnel like this I'd been in so the length surprised me a lot. About a week later though, I did a mile long tunnel (the same type as this one) that was over 50 feet under ground. I'm not exactly sure if this is trespassing or not. There obviously aren't any no trespassing signs and no one seemed to care. Still though it can be dangerous because if you somehow slip and fall with no one with you you'll have no cell service to call for anyone. Not even Life Alert could get you out of that problem. As with all of the things on this site I'm not going to directly state in the text the location but if you spend a minute looking you'll find it. Or just drive out there and look for a creek that mysteriously stops.