The Louisville Mega Space underground storage facility began as a crushed limestone quarry in the 1930s. Throughout the mid-twentieth century, workers mined more than 100 acres of limestone from the site, leaving a sprawling cavern with ceilings 90 feet tall. In 1989, the cavern was acquired by private investors who saw the potential to develop a portion of the cavern into an environmentally-conscious, high-security commercial storage facility.

Photo courtesy of Ralph Rogers Group.

Since the early 1990's, a massive amount of recycled concrete, brick, block, rock and dirt fill were used to create flooring and over 17 miles of roadway inside the cavern. Louisville Mega Space is classified by the Commonwealth of Kentucky as a building, and is the largest building in Kentucky at four MILLION square feet! Warehousing and commercial space construction is still in progress, and there’s no storage challenge too big for Louisville Mega Space.


  • The cavern was mined from the early 1930's to the early 1970's.

  • The mine goes under all 10 lanes of the Watterson Expressway (I-264).

  • The portion of the mine under I-264 was quarried before the highway was built in the early 1930's.

  • The Mega Cavern is approximately 100 acres.

  • Mega Cavern is classified by the Metro Louisville Government and the State of Kentucky as a building. As a matter of fact, it is the largest building in the State of Kentucky and has been given its own building code.

  • It took 12 years to receive an underground building permit.

  • The ground above and the underground below have separate zoning classifications. It is the only dual zoning area in Kentucky.

  • The underground is privately owned.

  • When you see a rock pillar, you are only seeing the top portion, which is approximately 25 to 30 feet tall. This is because the pillar was once about 85 to 90 feet tall before being backfilled with dirt and rock in order to create roads and warehouse space.

  • If you filled the Mega Cavern with boats, it could hold up to 16,000 units.

  • You cannot receive TV or radio signals in the underground.

  • There are 4 entrances/exits to the Mega Cavern; all together at the front.

  • The lowest entrance to the Mega Cavern is 25 feet above the top of the flood wall.

  • The underground is the largest recycling center in Kentucky by tonnage. It handles more material by tonnage than all others combined.

  • The average temperature in the Mega Cavern is 58 degrees year round.

  • Mega Cavern has two seasons; wet in the summer and dry in the winter

  • The average temperature for this part of the world over thousands of years is 58 degrees, which is the same as the cavern.

  • Each warehouse has the heater units inside of the building. Outside warehouses have the units outside of the building.

  • A 10 ton heater dehumidifies a 50,000 square foot building.

  • Utility costs are 75%-85% cheaper than the cost of a building not underground.

  • Most of the roads and warehouses in the underground have motion sensors that control the lights to conserve energy.

  • All buildings and road sprinklers have water in them and they will not freeze in the winter.

  • One building (warehouse unit) had a dance with 800 people and workers.

  • Air circulates through by natural air pressure, trying to equal the outside, similar to a stove pipe on a wood stove.

  • Supplemental fans are used to keep down the fog that can be created.

  • The #1 entrance to the cavern had an 8 inch snow fall one day when it was not snowing anywhere else in the city. This was due to moist air escaping from the cavern while hitting the below freezing temperatures outside the cavern......forming perfect conditions for a snowfall.

  • The walls of the underground buildings are made of sheets of Fiber-rock.

  • Walls of the buildings are hanging on a metal frame hanging from the roof.

  • Each wall of the building has a 2 hour fire rating.

  • A green building is a building built with energy savings incorporated into its construction.

  • The underground has radiant heat from rock, heavy insulation, motion detector lights, and recycles the heat from the lights and machines, as well as human bodies in the cavern. All of these items help it to be a green building.

  • Over 850,000 truck loads of backfill have been delivered so far to raise the floor up to the level that it is at today.

  • Each warehouse HVAC unit has an ultraviolet light to kill air born mold, mildew, and bacteria.

  • Approximately 70% of the Louisville Zoo is located above the cavern.

  • The limestone in this area is part of the Cincinnati Arch.


The mine was founded by Ralph Rogers back in the 1930’s. He was a great visionary who saw the need for highways in this country especially to the south. He was said to be able to look at a site and tell you just how much rock that he could get out of it. His business did very well; especially back during the Depression of the 1930’s when the government put people back to work by supporting the construction of new roads and bridges.

The Louisville Mega Cavern is a 100 acre limestone cavern capable of shrugging off a 260-mph tornado and boasts a constant 58-degree temperature. The cavern under the Louisville Zoo has remained virtually dormant since the last load of limestone was mined nearly 20 years ago to build bridges and roads across the Midwest.

In the post 9-11 world, government agencies and high security businesses are looking for ultimate security, and the Underground offers just that. With limestone and earth between the cavern ceiling and the ground above, the cavern could withstand the most violent tornado or an airliner crash.

During the Cuban missile crisis in the early 1960s, state officials made plans in case of nuclear attack to house 50,000 people in the cavern because it's a natural bomb shelter. With four entrances, positioned close together, access is easily controlled by a series of security checkpoints.

”Geologists say that this is the safest place in Kentucky," Jim Lowry, the co-owner, said.