A half-century after Washington severed relations with Cuba, the United States' seven-story mission looms over Havana's seaside Malecon boulevard as the largest diplomatic outpost in the country.
Cuban guards stand at close intervals on the street outside, and islanders line up by the thousands each year for a shot at a coveted visa.
The gleaming US Interests Section suddenly is poised to become an even more important presence in Cuba as the two countries negotiate the first phase of their historic detente transforming the complex into a full embassy that would reflect the Obama administration's hopes of new influence on the communist island.
Roberta Jacobson, assistant US secretary of state for Western Hemisphere affairs, will be the highest known US administration official to visit in decades when she comes next month for annual talks on migration that will now also focus on the details of re-establishing full diplomatic relations.
The discussions are expected to cover expanding staffing in the two countries' interests sections and letting diplomats travel outside their respective capitals without having to ask permission.
Also part of the reopening of the embassy: symbolic measures such as raising the American flag on the Malecon.
"Opening an embassy is a symbolic gesture, but symbols are really important," John Caulfield, who was Interests Section chief from 2011 to 2014, said by phone from Jacksonville, Florida, where he retired.
"This is a pretty powerful symbol by our president that we want to have a more normal relationship with Cuba despite the fact that we have the obvious differences," he added.
Cuba's interests section is a stately manor in Washington's Adams Morgan neighborhood. It, too, stands to become an embassy.
Diplomats say privately that Washington hopes to boost staffing in Havana, currently at about 50 Americans and 300 Cuban workers, as more American travelers and trade delegates are expected to come here under new rules to be set by the White House softening the US trade embargo on Cuba.
An agreement could also ease or scrap rules that require US diplomats to channel all requests through Cuba's Foreign Ministry; the diplomats would be able to deal directly with at least some other branches of government.
The US Interests Section has often been a flashpoint for conflict, and its decades of hybrid status reflect the dysfunctional relationship between the two deeply intertwined countries.
