The Haunted Cave in Lewisburg, Ohio, is 3,564 feet (1,114 m) long and 80 feet underground. The limestone cave also has something really spooky: 30,000 live bats!
The cave once held the world record for longest haunted house (back in 2010), though that title has since been taken over by other haunted house attractions. Regardless, the Haunted Cave remains popular with Halloween visitors, and was named the Best Haunted Attraction in the United States in 2018 by USA Today's Reader's Choice poll.
Not interested in scares? The Lewisburg Historical Society runs a historic wagon tour that explains the history of the limestone mine, with a good chance of seeing the bats.
Images: The Haunted Cave at Lewisburg