Raccoon Mountain Caverns, a show cave in Chattanooga, Tennessee, formed in Mississippian limestone on the Cumberland Plateau and became a visitor attraction after Leo Lambert explored cool air emerging from cracks at the mountain’s base in 1929. He enlarged the openings, discovered richly decorated passageways near U.S. Highway 41, and opened the cave to the public in 1931 as Tennessee Caverns. Later discoveries by the Smith Brothers expanded the public route into the modern Crystal Palace Tour, while wild cave trips began in the 1970s. More than 5.5 miles have been mapped, and the cave is also notable for fossils, active speleothem growth, salamanders, and a spider species found only there.