A new exhibit at the Transit Museum highlights the deconstruction of the Third Avenue El, as captured by Sid Kaplan, a curious New York City teenager with a camera, in the 1950s.

Starting as a steam-powered railroad in 1878, the Third Avenue El train offered above-ground service from South Ferry to Grand Central Depot, eventually extending service all the way up to 133rd Street in The Bronx.

But with the opening of the IRT’s Lexington Avenue line, ridership on the Third Avenue El began to decline as elevated trains fell out of favor. People saw the huge steel structures as shadowy eyesores that served primarily to hinder development. The line, Keith Williams wrote on Curbed in a history of the Upper East Side, made “this area a dangerous, lifeless place, creating an arbitrary dividing line between residential and commercial.”

Sections of the line began closing in 1950. In 1955, demolition began—and 17-year-old Sid Kaplan, who went on to become a master printer and photographer, was there to capture it on film. From his vantage point above the city—Kaplan took photos perched on rooftops and leaning out of office windows—he documented the end of the line, from the removal of the structure itself to the workers tasked with the project to the changing skyline of the city.

Kaplan’s work is now the focus of a Transit Museum exhibit called Deconstruction of the Third Avenue El. Housed at the Transit Museum’s Grand Central Gallery Annex, the exhibit features more than 40 of Kaplan’s early images, as well as a selection of related artifacts from the museum’s collections. The exhibit, which is free and open to the public, runs seven days a week through July 9.