Hidden under the streets of Iowa City is another world unknown to most people who walk above it almost every day.

Thanks to modern underground imaging technology, more is being learned about these pieces of the past then ever before, said Marlin Ingalls, a University of Iowa architectural historian.

“Instead of having to dig up these sites where we think a cave might be, we can look and see if anything’s down there,” Ingalls said. “This technology can be applied to cities and towns similar to Iowa City across the country for the same purpose.”

“I’ve already gotten calls from people in California who are interested in using the technology to find beer caves out there.”

The beer caves of Iowa City are where beer was brewed under the three breweries that once served Iowa City, the Union, Great Western, and the Englert, located around the aptly named “Brewer’s Square.” The Union Brewery, built in 1855, still stands on the intersection of Linn and Market Streets.

The Englert stood where there is a parking lot between El Banditos and High Ground, and the Union was in between George’s and the Bluebird Diner.  These sites became parking lots partially due to the city’s not entirely sure what lies beneath them, Ingalls said.

“We know that they’re down there; what we don’t know is how many of them or where exactly they’re located,” Ingalls said. “The city is hesitant to put a giant building on the spot when they don’t know exactly what’s down there.”

Kathleen Alling, who was at an event Thursday to inform the public about these caves, said she came because she recently returned from Portland, a city with many beer caves.

“I was interested to see if they take people down there for tours or if they could be developed at all,” she said. “I guess it would be too expensive, but I think a tour would be interesting if they ever open them up.”

Ingalls said redevelopment of the caves has come up, but the price would be around $750,000, and it would be almost impossible to get equipment into them.

The caves are currently closed to the public because of safety concerns.

“There’s no stairway or elevator down there; it takes a 20-foot ladder to get to them,” Ingalls said. “It’s more like spelunking than a walking tour.”

The beer caves are not the only subterranean structures in Iowa City.

Barb Stimmel came to learn about the caves because of stories she heard from her father about ice caves in City Park.

“I’m always interested in history, especially Iowa City history,” Stimmel said. “I really want to go down and see them. I think it would be very interesting.

There are caves in City Park, which was used to store ice before refrigeration, and tours for the Brewer’s Square beer caves will be starting soon, Ingalls said.

“The caves in City Park are toward the back parking lot, and they’re rumored to be long enough to turn a semi around in,” Ingalls said. “We’re doing the first tours later this month; we want to try to make it a monthly event.”

That is just the tip of the underground iceberg in Iowa City. Tunnels run extensively downtown and are still used by many businesses and accessed through those metal doors on the sidewalk.

The University of Iowa also has an extensive tunnel system; almost 14 miles of steam tunnels run under the campus and are still in use today.

“It’s very hot and very dangerous; they don’t let just anyone in there,” Ingalls said.

“Sometimes I’ll get asked if I’ve ever found the bones of a student or old beer cans down there,” he said. “It hasn’t happened yet; I think that’s probably why they keep them closed.”