For the past few weeks in this space, we’ve been hanging around the Steuart Building at Fifth and K streets NW, the top floors of which were home to the CIA’s National Photographic Interpretation Center from 1956 to 1963. The place buzzed in October 1962 when Soviet nuclear missiles were photographed in Cuba.

Even the most closely held secrets can be hard to keep. Jim Allen’s father, George, was in the Steuart Building for a few years when he was part of a small contingent from the Army Map Service that worked there with the CIA.

Wrote Jim, of Fairfax Station: “He told me that he once got a cab to go there and when my dad told the cabdriver the address, the cabdriver said, ‘Oh. You’re one of those CIA guys.’”

Dave Stinson said there was a CIA print shop on the top floor of the building, with print jobs laid out on skids.

“On our hot D.C. summer days the large industrial-size windows were kept open,” he wrote.

One day, a massive summer thunderstorm hit. Papers blew out through the windows and fluttered to the ground below. Wrote Dave: “The area was filled with government employees collecting the wind blown documents!”

Chris Hughes’s father, John T. Hughes, worked in the Steuart Building, first as a photo interpreter for the Defense Intelligence Agency, then as a national security briefer.

Wrote Chris: “Half our neighborhood in Annandale was working overtime during October 1962 — a lot of neighbors were in the intelligence community. He told my mom nothing about why he couldn’t come home for those two weeks but said to fill the car with food and water and if anything happens, take the kids and go west.”

After tensions had died down, John F. Kennedy wanted the nation to understand what had happened. Defense Secretary Robert McNamara asked John Hughes to deliver a televised security briefing in prime time. (You can find it on YouTube.)

John had to sort through images, finding ones that weren’t classified. The visual aids were projected on a 10-foot-high screen.

“He didn’t have a long enough pointer that day,” wrote Chris, of Herndon. “In order to point out a feature up high on the screen, he used two fishing poles someone had in their car trunk. Taped together he could then point to the top of the screen.”

Carolyn Harwood worked in the Navy Yard in the 1970s and 1980s. Her carpool used to pass a building near there that had “Photographic” in its name. Wrote Carolyn: “Do you know whether the CIA had an office there?”

Answer Man suspects she’s referring to Building 213, which became the home of the NPIC in 1963 after the organization had outgrown the Steuart Building.

Unlike the Steuart Building, Building 213 — on the southeast corner of First and M streets SE — was a government office building, more obviously secure. It was encircled by a chain-link fence topped in barbed wire.

Jack O’Connor, a retired CIA intelligence officer and author of “NPIC: Seeing the Secrets and Growing the Leaders: A Cultural History of the National Photographic Interpretation Center,” said that when an extension was built onto the building between 1984 and 1988, the chain-link fence was replaced with a wrought-iron fence and brick-faced concrete columns.

“Also at that time, the name of the organization was put over the entrance — National Photographic Interpretation Center — so your reader in the carpool is not misremembering,” he wrote.

Morgan Birge II of Fredericksburg, Va., worked in Building 213 from when it opened in January 1963 until the late ’90s. Among his memories is watching Mike Wallace of “60 Minutes” fame argue with a guard at the gate, attempting to get the guard to admit it was a CIA facility. Wallace was instructed to call a phone number for more information.

Because of the classified work in Building 213, the documents generated there were marked with their security classification. That included the cafeteria menu. “Perhaps well deserved,” Morgan said. “The way the food was, they needed to do that.”

Morgan said that to obscure the nature of the work going on inside 213, the big yellow boxes of film supplies coming from Eastman Kodak were rewrapped in plain paper before delivery.

Not all the work related to national security. The U.S. Geological Survey occupied part of the sixth floor, accessible by an outside elevator that bypassed the secret stuff.

“This office investigated the rocks brought back from the moon,” Morgan wrote.

Today, NPIC’s descendant — the National Geospatial-Intelligence Agency — is in Springfield. Building 213 was demolished in the summer of 2014. Washington Nationals fans may remember walking past its location on the way to the ballpark. There was a trapeze school on the block that once held the top-secret facility.