UNDERGROUND CAVES. Today I'd like to share with you what I learned on Wickipdedia.
It is dug into Bethany Falls limestone mine and it is at 160 feet beneath the surface. It containes seven miles of paved roads and several miles of railroad track.
The mine maintains a temp of between 65 and 70 degrees Faharenheit year-round.
SubTropolis houses around 50 businesses and organizations.
To name a few:
US Postal Service
Also the caves sponsor the Annual "Groundhog Run" which is celebrating it's 31st year in 2013 for Children With Disabilities.