Located within a Tennessee mountain is the tallest subterranean cave waterfall in the United States, accessible through a glass elevator ride.

How to visit Tennessee’s Lookout Mountain’s magnificent Ruby Falls near Chattanooga.

If you’re not sure if nature has a sense of humor, consider this: One of the most stunning natural wonders in the U.S. is hidden within another gorgeous American natural landmark. Ruby Falls, the tallest and deepest underground cave waterfall in the U.S. that’s open to the public, is set inside Lookout Mountain, which itself is one of the area’s top attractions.

Both sites are located in Chattanooga, Tennessee, a southern town known for its rock climbing, biking, and hiking. And while you’ll see plenty of people lined up to ride the glass-roofed Incline Railway up Lookout Mountain, the real gem is found inside the peak.

COURTESY OF RUBY FALLS

The journey begins with a glass-front elevator that descends 26 stories into the heart of the mountain. At the bottom, visitors will see a series of stalactites, stalagmites, ancient formations, and of course, Ruby Falls, which is set 1,120 feet within Lookout Mountain.

In order to keep the underground cavern well-preserved and visitors safe, all visits to Ruby Falls must be guided. The popular Cave Walk tour offers a faster-paced journey through the cave to the waterfall with pre-recorded audio. There is also a before-hours Gentle Walking Tour with more in-depth information and an after-hours Lantern Tour.

COURTESY OF RUBY FALLS

Those visiting around Valentine’s Day this year can book the Romance at Ruby Tour, which takes place Feb. 10, 11, and 14. This romance-focused journey delves into the falls’ past. Leo Lambert, who came across the falls in 1928, named the discovery after his wife, Ruby.

If a February visit isn’t in the cards, don’t worry, Ruby Falls is open year-round and boasts 60-degrees-Fahrenheit average temperatures in all four seasons.In addition to seeing the underground cave and waterfall, travelers to Ruby Falls can climb the neighboring Lookout Mountain Tower and Blue Heron Overlook for sweeping views of the valley and the Tennessee River. High Point ZIP Adventure, a series of zip lines and a climbing tower, is also situated near Ruby Falls on Lookout Mountain.