* What: A 145-foot high waterfall located 1,120 feet beneath Lookout Mountain. Ruby Falls, within the underground cave, was formed over the past 200 million years and is now America's deepest commercial cave and largest underground waterfall open for public viewing.
* History: In 1905 the natural entrance to Lookout Mountain Cave was closed during the construction of a railway tunnel. In the 1920s a chemist and cave enthusiast named Leo Lambert tried to re-open the cave and discovered an underground waterfall in 1928. In 1930, Ruby Falls began hosting visitors.
* Origin of the name: Lambert named the falls after his wife, Ruby. It was popularized with billboards across the South urging motorists to visit the Lookout Mountain attraction.
* What's ahead: The entrance-way, parking and retail facilities above the historic falls soon will get a new look. Over the next decade, the owners of one of Chattanooga's biggest tourist attractions plan to invest more than $20 million to upgrade the facility and more than double the building space on the side of Lookout Mountain.
PGAV Destinations, a tourism design and consulting firm, helped develop the 12,000-square-foot expansion, visitors mall and parking improvements. The upgrades follow last year's installation of high-speed Wi-Fi within the cave so visitors who use Snapchat or other social media can share their experience instantaneously.
"History is to be embraced, but it's also to be enhanced," said Hugh Morrow, president of Ruby Falls for the past eight years.
* Owner: John T. Steiner Family Trust.
* Location: On 12.5 acres along Scenic Highway on the side of Lookout Mountain.