"This is like we’re back in the Roman times," said Chief Operating Officer Marty Adams with Los Angeles Department of Water and Power.

No, it's not an ancient ruin, but rather construction on what will be the largest underground water storage facility in the Western U.S.

"Somebody goes, are they building a Costco over there?"

He offered a sneak peek inside this rare sight near Griffith Park. Adams is one of the people in charge of the future Headworks Reservoir Complex. It's made up of two reservoirs. East was completed in 2014 and the West is now being built.

"There’s about 360 columns like this. These columns are here to hold up the roof," Adams explained.

Each column is around three stories tall. Adams pointed out a huge pipe that runs below ground—sending water throughout the Los Angeles area.

"The average flow is about 750 gallons a second, so it’s basically about two average home pools a minute, about 65 million gallons a day," Adams said.

The complex will replace the Silver Lake and Ivanhoe Reservoirs, which are now out of service. New federal rules required the LADWP to cover open air reservoirs or replace them. Underground reservoirs are designed to be more protected.

"This is really a water quality project to meet standards that the old reservoirs would not have met," Adams said.

But Jessica Freeman and others worry about the future of Silver Lake and Ivanhoe reservoirs in their backyard.

"This is a really special place for our community," Freeman explained.

"Even though it’s manmade, it really is the landscape of our neighborhood. If it didn’t exist, it wouldn’t be our neighborhood at all."

She says it's a peaceful place for neighbors to workout or walk their dogs.

"There’s been fantasies in the neighborhood of turning it into some kind of swimming spot. That would be pretty cool or even just some kind of a space where we could walk even closer to the perimeter," Freeman said.

"The question is whether you should be able to look at the water, or walk around the water, or go in the water," Adams said.

As for the Headworks Complex when it opens in three years . . .

"It’ll all be buried and out of sight. Then, this site will be restored to something better than it ever was," Adams said.

The hope of area residents is that it's turned into some type of green space with a park and paths for everyone to enjoy.