On a sparkling day in Venice, Italy, the orange curtains of a gondola’s canopy provide shade from the white heat reflecting off the water. Its translucent cloth casts a reddish haze over Ramón Subercaseaux, who sketches a drawing of John Singer Sargent while the unseen artist busily paints a portrait of the Chilean diplomat.

When the exhibit featuring this painting, “Sargent’s Venice,” opens at the Adelson Galleries on Thursday, viewers will be swept along with both men down the city’s undulating thoroughfare. Gondolas are not included, but the show will be arranged so that viewers can see the ancient city as Sargent did: with an eye to its unusual interplay of shadow and light on the decaying splendor of its architecture.

The portrait of Subercaseaux sitting in a flat-bottomed boat in the place once called La Serenissima, the world’s most serene city, is one of the highlights of the 60 oils and watercolors in the show, which will travel to Venice’s Museo Correr in late March. It has taken more than 120 years since the piece was painted for a show focusing solely on Sargent’s work in Venice to be put together, the curators say.

The exhibit is to coincide with the publication of a book by the same name — and both have been in the works for the past two and a half years.

In addition, this is also the first time that the people of Venice will have the opportunity to see the artist’s vivid, Impressionist-inspired images of their hometown. The Florentine-born American expatriate artist, who loved to paint Venice more than any other place, never had a solo exhibit there while he was alive — nor in the intervening 80 years since his death in 1925.

“We all knew ‘Sargent’s Venice’ was a subject waiting to happen,” the artist’s great-nephew and a coauthor of “Sargent’s Venice,” Richard Ormond, told The New York Sun. “I can’t say there was a particular moment when the penny dropped. But once it did, it was obvious that Venice had to be one of the locations” where the exhibit should appear.

Mr. Ormond, who is also a co-author with Warren Adelson of “The Complete Paintings of John Singer Sargent (Yale University Press), noted the success of an earlier Sargent exhibition in Ferrara, Italy (about 60 miles from Venice), in 2002. “Venice was a natural sequel,” he said.

A few of the pieces are on loan from pre-eminent institutions such as the Brooklyn Museum, the National Gallery of Art in Washington, and London’s Royal Academy of Arts, but most of the work comes from private collections where it is rarely seen by the public. The pieces will include Sargent’s pictures of the Doges Palace, the Rialto Bridge, and Santa Maria della Salute, as well as scenes of ordinary Venetians chatting in cafés, buying wine, and taking naps in the somnolent heat of the Mediterranean.

But the question remains: For an artist who ventured to Venice from his home in England dozens of times over 40 years to paint images of the city, why has it taken so long for a solo exhibit of his work to appear there?

Mr. Adelson, the president of Adelson Galleries, offers an explanation by pointing out that the watery port was not seen as an important art center during Sargent’s lifetime.

“It was considered an art colony,” he said, calling it a place to which painters traveled for inspiration before leaving to exhibit their work in Paris or London.

“The same way the Hamptons were for the Abstract Expressionists,” he added. “Willem de Kooning painted in East Hampton, but he exhibited in New York.”

The gallery’s director, Elizabeth Oustinoff, another co-author of “Sargent’s Venice,” suggests that the long lag time also may have been due to difficulties in determining exactly when Sargent painted many of the works in the exhibit, which often are unsigned and undated.

“The show would be difficult for others to have done because there are a lot of dating issues, especially with the watercolors,” Ms. Oustinoff said, adding that Adelson Galleries’s unique expertise on the artist’s stylistic development allowed them to finally pin down the likely chronology of the undated pieces.

According to Mr. Ormond, the artist’s watercolors are particularly significant because “you don’t have to know much about art to appreciate Sargent’s watercolors. They are full of light and movement and color.”

“He can conjure up a scene in a few swift strokes — boom!” Mr. Ormond said. “There it is and so alive.”

Until March 3 (19 E. 82nd St., between Fifth and Madison avenues, 212-439-6800).