Stonington -- A crowd gathered at the intersection of Water and Union streets in the borough Sunday afternoon to celebrate the federal government’s decision to name the adjacent home of late Pulitzer Prize-winning poet James Merrill a National Historic Landmark.

The designation means the town now has six national historic landmarks including the Nathaniel Palmer House and four vessels at Mystic Seaport, including the Charles W. Morgan. It is also one of five landmarks in the state related to writers, such as Mark Twain, but the only one related to a writer from the mid- to late 20th century. The Department of the Interior had made the initial announcement in November.

“I know he also lived in New York, Greece and Key West but this was his home,” First Selectman Rob Simmons said about Merrill during Sunday’s ceremony. “This is where he wrote some of his greatest poems.”

Simmons, who knew Merrill, called him “smart, sophisticated and gifted ... but he did not push any of those attributes.”

“It was just who he was,” he said.

Moments before the unveiling of a facsimile of the plaque that will be affixed to the front of the house noting its landmark status, Simmons looked to the sky and said, “Jimmy, wish you were here. But you are here in spirit.”

Merrill and his partner David Jackson moved to the third floor apartment at 107 Water St. in 1954 and lived there until Merrill’s death in 1995. His apartment and its fixtures were left intact and since 2008 it has hosted a writer-in-residence program in which visiting scholars and writers stay in the apartment for various periods of time. The home, which remains the way it was when Merrill and Jackson lived there, is owned by the Stonington Village Improvement Association.

Merrill, whose writings were influenced by borough life, won every major poetry award in the United States including awards for some of his best-known works, such as “The Changing Light at Sandover” and “Divine Comedies.”

Merrill’s biographer Langdon Hammer, a Yale professor, told the crowd that the irony of Sunday’s celebration is that Merrill and Jackson moved to the borough in 1954 to be private. He said Merrill was “allergic to civic monuments and historic occasions.”

He said Merrill and Jackson’s apartment “is a time capsule” which takes people back to an era when gay life was hidden.

Hammer, who read from one of Merrill’s books of poems, said the poet would sit at his desk with his back to the view of Stonington Harbor, while “patiently and doggedly” creating a great volume of work. He said that the same doggedness was shown by the group of residents who have worked to preserve the home, have it named a landmark and create the writer-in-residence program.

Merena Wisniewski, the state architectural historian, told the crowd that the home also helps document the state’s LBGQ heritage.

Secretary of the State Denise Merrill was among the dignitaries on hand and read a proclamation of congratulations on the designation.