VALMEYER, Ill. — There's an underground city not far from St. Louis. It's complete with city streets, fire hydrants and lighting, and it attracts some pretty big tenants.

It all started in the late 1800s.

"When the original miners first came to old Valmeyer, I guess they founded Old Valmeyer," said Joe Koppeis of Admiral Parkway, Inc. "They called it rock city and it grew from there.

After the flood of 1993, the town of Valmeyer moved to higher ground. They also brought the mineral rights to the old mine. Koppeis saw an opportunity. His company manages Rock City, which is home to multiple companies and about 500 employees.

At the facility, you'll find all the amenities of a regular office space, including streets and lighting maintained by the Village of Valmeyer.

And while building underground may seem like a challenge, it comes with plenty of perks.

"We're earthquake-proof, electromagnetic-proof, we're tornado-proof, we're ice-storm-proof," Koppeis said. "Nothing can really impact what we have underground,"

In addition to defense from the elements, underground structures like this are ideal for refrigeration operations and a whole lot more.

Even the US government is taking advantage of this rock-solid opportunity.

"The national archive actual has office space here. It's class-A office space and then we have about two-and-half million boxes of federal records they store, maintain and operate," Koppeis said.

There's still about 4 million square feet of space to develop, and plans could even include an Ice rink.