A crowd gathered on a sidewalk under a scorching sun. One man pounded out beats on a conga drum. A woman approached people on the sidewalk, handing out chicken empanadas.
They were celebrating the historic event transpiring in front of an elegant old building: the reopening of a Cuban Embassy in the United States after 54 years, with the hoisting of the lone-star flag above the property.
A similar scene was playing out in Havana — though the raising of the stars-and-stripes won't happen there until Secretary of State John Kerry visits next month.
Monday's events came seven months after the stunning announcement that the U.S. and Cuba would work to normalize relations, following secret negotiations mostly conducted in Canada.
Even in the celebratory atmosphere, however, there was ample evidence that the long-dysfunctional Cuba-U.S. relationship still falls far short of normalcy.
The Castro government says a few conditions need to be met first. Some of them were listed on signs posted by an anti-war group onto the fence at the just-reopened Washington embassy.
They read, "Lift U.S. (trade) embargo now!" and "Lift U.S.-imposed travel restrictions" and "Guantanamo for Cuba, U.S. off Cuban soil," succinctly summing up the Cuban demands.
Recent developments mean the old Cold War foes can now have diplomats in each other's countries. Americans can travel far more easily to Cuba, for a variety of cultural reasons, and can buy plane tickets directly. And banking and telecommunications are expected to open up on the island.
What remains unresolved are the numerous trade restrictions enshrined in U.S. legislation. There's no evidence of Congress seeking to undo them, and there could also be a fierce fight with lawmakers over the confirmation of an ambassador to Havana or the budget for the new U.S. embassy there.
A few notes of ambivalence could be heard amid the celebratory street scene.
One man wearing a red Che Guevara T-shirt said he'd come in from his Virginia home to witness what he hailed as a positive step, and to offer his support to the Cuban government.
But he said he has some concerns.
Ramon Perez said he wants a freer economic and political system in Cuba. But the Puerto Rico-born man listed his fears: that the corporate-driven U.S. political culture could spread to Cuba; that the U.S. might work to overthrow, or run, the Cuban government; that exiles might try to take back nationalized property.
"I do worry," he said.
"I don't want Cuba to become just another Latin American country that bends to the dictates of the north."
Similar concerns were being expressed inside the building.
Even as he toasted the new relationship, Cuba's foreign minister reached into history to illustrate that troubles in the relationship with the U.S. long predated the 1959 revolution.
He noted that Cuban independence hero Jose Marti had lived in the U.S., and had extolled the country's virtues, but had also warned against what he called an excessive American craving for domination.
Bruno Rodriguez Parrilla spoke of U.S. military occupation in 1899, the annexation of Guantanamo Bay that followed, and the refusal later to accept the socialist revolution.
"There have never been normal relations between the United States of America and Cuba," said the foreign minister.
"Today an opportunity has opened up to begin working in order to establish new bilateral relations, quite different from whatever existed in the past. The Cuban government is fully committed to that."
The Cuban government is working on a long-term economic plan for what President Raul Castro described in a speech last week as "sustainable socialism."
What anti-Castro expats in the U.S. want is regime change. One son of Cuban immigrants, Sen. Marco Rubio, said he'd reverse recent moves if he wins the presidency.
"I would end the diplomatic relations with an anti-American communist tyranny, until such time as they actually held a democratic opening in Cuba, allowed people to organize independent political parties, have freedom of the press and freedom of expression," Rubio told CNN over the weekend.
"And that would include the return of fugitives from American justice that are now in Cuba."
The White House refrained from speculating Monday on next steps, such as the naming of an ambassador or the possibility of an Obama visit to Havana.
Just up the road, on 16th Street, the Cuban flag — which was designed by 1840s revolutionaries exiled in the United States — was back up, flying again in its country of origin.