A flagpole is erected on the front lawn of the Cuban Interests Section on 16th Street NW in Washington. (David Montgomery/The Washington Post)

Peter Mullaly, owner of Eastern Shore Flagpoles, stood across 16th Street NW from the handsome limestone mansion that is the Cuban Interests Section on Wednesday morning and hollered to his crew of flagpole erectors working in the front lawn:

“Maybe a little more to the right! Just a pinch that way! Just a pinch!”

The workers nudged a 30-foot anodized aluminum pole a hair to the north. Mullaly eyeballed the pole, comparing it to vertical lines of windows and columns. “The eye is the last tool,” he explained to a reporter at his elbow.

Finally, Mullaly was satisfied that the pole was precisely vertical. “Good!” he declared.

For the time being, no flag will fly from the pole. Strict protocols, tensely negotiated decades ago, forbid flags. Topped with a gold-colored ornamental aluminum ball, the pole stands incongruously unadorned on that boulevard of so many diplomatic installations.

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Yet one day, perhaps not long from now, the red, white and blue Cuban banner could flutter in front of the mansion for the first time in more than half a century. You can’t have a flag without a flagpole, so erecting this one was an anticipatory step in geopolitical history.

Jose Ramon Cabanas (light blue shirt), chief of the Cuban Interests Section, is among those who watched the installation of the flagpole. (The Washington Post/David Montgomery) José Ramón Cabañas (light blue shirt), chief of the Cuban Interests Section, is among those who watched the installation of the flagpole. (David Montgomery/The Washington Post)

“I’m proud to be part of it,” said Mullaly, who has erected numerous flagpoles around town, for embassies, government offices, hotels, even The Washington Post. “I’ve done many jobs. This is the one that’s been the most important. Not the biggest, but I would say the most important. It’s such a historic moment.”

After several rounds of talks since December, when President Obama and Cuban President Raúl Castro announced their intention to restore relations, Cuban and American diplomats have been working toward the day when their respective interests sections might be upgraded to embassies, ambassadors could be exchanged and flags could once again fly from flagpoles.

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Cuban officials declined to comment. A person familiar with their thinking said the construction was not an official ceremony and had nothing to do with the pace of diplomatic talks between the two nations.

Nevertheless, a couple dozen officials and members of the Cuban diplomatic community gathered on the lawn to watch the installation of the flagpole. When the job was done, they sang the Cuban National Anthem.

A small group of reporters and camera operators who had caught wind of the unique construction project — there was no press release or official announcement — stood on the sidewalk outside the locked iron gates. Cubans who happened to be across the street at the consular office on passport business hurried over to watch the flagpolers from Queenstown, Md., do their work.

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“I’m very moved,” said Fernando Rodriguez, 51, who came from Matanzas, Cuba, to Lancaster, Pa., five years ago. His wife, Basilia Quintero, 50, immigrated four years ago. “This new opening of relations is going to open the door to a better economic situation, a better family situation” in Cuba.

“We’ve been waiting for this for a long time,” Quintero said. “We feel very happy.”

They couple said that the tough economy in Cuba drove them to immigrate in order to help their family. If the new relationship with the United States leads to better opportunities to make a living in Cuba, they said, they would think about returning to their homeland.

Basilia Quintero and Fernando Rodriguez, who immigrated from Cuba, felt lucky to have been present by chance to see the flagpole go up. (David Montgomery/The Washington Post) Basilia Quintero and Fernando Rodriguez, who immigrated from Cuba, felt lucky to have been present by chance to see the flagpole go up. (David Montgomery/The Washington Post)

The Cuban government built the colonial revival mansion at 2630 16th St. NW in 1916-1919 to be the embassy, according to a history compiled by David Maloney, the state historic preservation officer for the District of Columbia. (Following independence from Spain in 1902, Cuban diplomats had been working out of other quarters in town.) The building is considered significant in the architectural history of Washington because it was the first purpose-built embassy in the Meridian Hill neighborhood, helping establish Meridian Hill as a diplomatic center. The structure is a prime example of the City Beautiful Movement in Washington.

Headlines at the time saluted the new edifice: “Cuban Legation Home: Style to be Louis Quinze, Building with Indiana Limestone Exterior and White Marble Interior Will Be One of the Handsomest Occupied by Diplomats in Washington.”

The Washington Post covered a garden party in 1938: “Enthusiastic comments straying in from every side proved that the hospitable embassy on Sixteenth Street with its large, deep garden still holds first place as society’s favorite setting for outdoor events.”

The day after Fidel Castro toppled dictator Fulgencio Batista in January 1959, an ambassador for the revolutionary government took charge of the embassy in Washington. Castro visited later that year and was hailed at receptions in his honor.

The United States broke diplomatic relations with Cuba in early 1961, and by early 1962 the last Cuban diplomats had departed. Czechoslovakia maintained the building for a number of years.

A plaque explains that, for now, the Cuban Interests Section is sponsored by the Swiss Embassy. (David Montgomery/The Washington Post) A plaque explains that, for now, the Cuban Interests Section is sponsored by the Swiss Embassy. (David Montgomery/The Washington Post)

In the late 1970s, in a gesture toward improved relations, Cuba and the United States agreed to open interests sections in Havana and Washington. An interests section is less than an embassy, presided over by a chief-of-mission, not an ambassador. The U.S. Interests Section is located in the former U.S. Embassy in Havana. The Cuban Interests Section in Washington and the U.S. Interests Section in Havana each operate under the auspices of the Swiss government.

The interior of the century-old mansion on 16th Street has been well-preserved. In the last year or so, some of the same craftspeople and artisans who have helped restore classic buildings in Old Havana completed preservation projects at the interests section.

Equally well preserved, for now, are the old artifacts of mistrust and spite. When the interests sections opened, restrictions were imposed. Cuban diplomats may not venture outside the Beltway without permission from the U.S. government. American diplomats in Havana face similar limits on travel.

And the nations agreed that neither would fly its flag in front of its interests section. The flagless pole on 16th Street NW is the last symbol of a passing era.