This is the entrance to Island Ford Cave, between Covington and Low Moor, Virginia. You'd never know it was there from driving I-64 (directly behind the photographer). It's on a "frontage road" that may very well have been US 60 at one time. The signboard inside states that the cave extends 550 feet deep. Amazingly, it does not forbid exploring the cave. However, I left my flashlight at home, so I passed on it.