Tucked below English Mountain at the eastern edge of the Great Smoky Mountains sits a picturesque series of caves. They are not unlike many of the 8,000-some-odd caverns that dot the Tennessee landscape, but for the fact that these caverns are lit up like Oogie Boogie’s lair in The Nightmare Before Christmas.

The Forbidden Caverns stretch for a half mile and feature eerie and arresting mineral formations, echoing grottoes, silent reflecting pools, and a clear, cool stream likely fed by a nearby underground lake.

The caves have been hospitable to human activity for centuries, from the indigenous peoples who frequently sought shelter here from mountain winters, to moonshiners who operated stills here from the early 1920s to the early 1940s. One chamber boasts a remarkably large wall of flowstone or “cave onyx”—a type of rock formation highly prized as an architectural ornament in the 19th and 20th centuries. This stretch was, thankfully, left intact.

The caves were outfitted as an inviting edutainment venue and opened to visitors for guided tours in 1967. Groups are conducted through places like the “Grotto of Evil Spirits” and the “Grotto of the Dead,” while light shows, sound presentations, and guides highlight the history and legends associated with the Forbidden Caverns. The temperature, reportedly, is always 58°F (14.4°C).