4200 N Interstate 35 Frontage Rd.
Georgetown, Texas 78626
Hidden for 14,000 years, Inner Space Cavern is 4.76 miles of cavernous passageways directly underneath IH 35, making us the 5th longest cave in Texas.
Inner Space Cavern was discovered in 1963 by the Texas Highway Department.
During regulation core testing, the highway department drilled several core samples down through the ground and wound up drilling in to the top of the cave.
They searched all over the surrounding area but could not find an access into the cave.
So they drilled a two foot wide hole down through 33.5 feet of limestone bedrock.
The hole, known as the Discovery Hole, was the only entrance to the cave for several months.
There are almost 5 miles of cave passage way connected to Inner Space Cavern, making it the fifth largest cave in Texas.