Gilmerton Cove is a mysterious underground network of tunnels and chambers carved from sandstone beneath the streets of Gilmerton, a suburb of Edinburgh, Scotland. No one really knows for sure why it was created, but theories range from being a secret drinking den to a meeting place for the Hellfire Club. Some recent research suggests that the Cove may be even bigger than what's currently uncovered. It's like a real-life hidden gem waiting to be explored!