Charles Trew of Arlington, an espionage buff, believes that this is where the FBI dug a tunnel to listen in on Soviet diplomats. The Russian Embassy is directly behind the house. (John Kelly/THE WASHINGTON POST)

In the 1970s, John Galuardi served as the regional administrator for the GSA in Washington. One of his tasks was to figure out what to do with the land on which the empty Mount Alto Veterans Hospital stood.

[Scaling Glover Park’s Mount Alto: From VA hospital to Russian Embassy]

This encompassed 12 1 / 2 acres between Wisconsin Avenue and Tunlaw Street NW in Glover Park. John was thinking about placing some government buildings there when the State Department announced that it would be the home of the new Soviet Embassy.

“The property was totally abandoned, and we had just let it deteriorate,” John wrote in an email to Answer Man. Why do maintenance when the buildings were just going to be torn down?

As it turned out, John had to do a little maintenance after all. One day, some FBI agents came to his office. They asked John to send workers to Mount Alto to cut down three trees on the edge of the property. Russian architects were coming the following week, and the FBI wanted the trees gone.

Also: It should not look as if any trees had been cut down.

“I said, how do you expect me to cover up the sawdust from the chain saws?” wrote John.

John had a crew cut down the trees and clear the whole site around the buildings. The crew also made it look as if grass seed was going to be planted, covering the area where the trees had once stood.

Wrote John: “Apparently it worked.”

Why the sudden FBI interest in arboriculture? Answer Man can only assume that the G-men wanted an unobstructed view of the property, the better to monitor comings and goings.

[Diplomatic impunity: Squashing the bugs infesting our embassy in Russia]

Last week in this space, we recounted the tortured history of the U.S. Embassy in Moscow and how those sneaky Communists crammed it full of listening devices as it was being built. Surely the Americans would never do something so sneaky?

Ahem. In January 1980, Soviet officials announced that eavesdropping devices had been found in a new apartment building for embassy workers on the Mount Alto site. An article in Izvestia said the bugs allowed the FBI and CIA to hear “every sound, from a word spoken in the drawing room to a whisper in the bedroom or a splash of water in the toilet.”

That, however, was not the most audacious effort to listen in. When FBI turncoat Robert P. Hanssen was arrested in 2001, Count 2 of his indictment charged that he had revealed to his Soviet handlers the “existence of an FBI technical penetration of a particular Soviet establishment, as well as the specific location of the penetration device, and the methods and technology utilized.”

The penetration device, sources later revealed, was a tunnel under the Soviet Embassy built by the FBI and operated by the National Security Agency. It probably cost hundreds of millions of dollars.

Although they of course already knew about it, Russian officials went through the show of summoning an American diplomat in Moscow to explain the tunnel.

“If these reports prove true, this will be a flagrant case of the violation of generally recognized standards of international law concerning foreign diplomatic missions,” the Russian Foreign Ministry said in a statement.

As it happened, a U.S. official said the FBI-NSA tunnel might have been inspired by the Soviets themselves. In 1978, a tunnel filled with listening devices was discovered beneath the old U.S. Embassy in Moscow.

Residents of Glover Park were abuzz. If the tunnel ended under the Soviet Embassy, where did it begin?

Some thought the entrance was in a house on Wisconsin Avenue facing the embassy’s entrance. But that would require tunneling under the busy road. (More likely, that was a place from which the FBI could watch the embassy.)

Others thought it was a house on Fulton Street, at the end of Bellevue Terrace, about as close as it’s possible to get to the Russian compound.

Charles Trew, an espionage buff who studied Russian in college, has been obsessed with the house for about 10 years. He lives in Arlington and has visited the spot frequently. No one has ever been home, even on Halloween.

Last week, Answer Man visited the house with Charles, who was surprised to see that it has been gutted. A porta-potty sits in the driveway. The roof is gone. One garage door has fallen off its tracks.

Charles pointed out the oddly raised wooden floor in the garage at the back of the house, overlooking the embassy. He noted that the garage windows are black glass.

Charles said some naysayers believe that since the house sits on a bluff, it’s too high for a tunnel. He said a tunneling expert told him that when it comes to tunnels, it’s easier to dig down than across.

“I’m convinced,” he said. “There simply are no other realistic candidates.”

In a 2013 presentation at the Spy Museum, David Wise, author of a book on Hanssen, said that wherever the tunnel entrance is, it has been sealed with cement.

Calls to the company remodeling the house were not returned. Answer Man contacted the FBI to see whether it wanted to use his column to finally announce exactly which house harbored the ill-fated tunnel. The reply: “We have no comment.”

Twitter: @johnkelly

Unlike the FBI and the KGB, Answer Man does not have listening devices at his disposal. If you have a question about the Washington area, you must send it to answerman@

washpost.com.

For previous columns, visit washingtonpost.com/johnkelly.