The project was four years in the making, part of the department’s mission to make city records accessible to everyone, said department assistant commissioner Kenneth Cobb.

“We all knew that we had fantastic photograph collections that no one would even guess that we had,” Cobb said.

Taken mostly by anonymous municipal workers, some of the images have appeared in publications but most were accessible only by visiting the archive offices in lower Manhattan over the past few years.

Researchers, history buffs, filmmakers, genealogists and preservationists in particular will find the digitized collection helpful. But anyone can search the images, share them through social media or purchase them as prints.

The gallery includes images from the largest collection of criminal justice evidence in the English-speaking world, a repository that holds glass-plate photographs taken by the New York City Police Department.

It also features more than 800,000 color photographs taken with 35mm cameras of every city building in the mid-1980s to update the municipal records, and includes more than 1,300 rarely seen images taken by local photographers of the Depression-era Works Progress Administration.

Because of technological and financial constraints, the digitised gallery does not include the city’s prized collection of 720,000 photographs of every city building from 1939 to 1941. But the database is still growing, and the department plans to add more images.

Eugene de Salignac

Among the known contributors to the collection was Eugene de Salignac, the official photographer for the Department of Bridges/Plant & Structures from 1906 to 1934. An iconic Salignac photograph, taken 7 October, 1914, and now online, shows more than a half-dozen painters lounging on wires on the Brooklyn Bridge.

“A lot of other photographers who worked for the city were pretty talented but did not produce such a large body of work or a distinct body of work,” said Michael Lorenzini, curator of photography at the Municipal Archives and author of “New York Rises” that showcases Salignac images.

Maira Liriano, manager of the New York Public Library’s local history and genealogy division, said the tax photo collections are of particular interest to researchers.

For example, she said, homeowners seeking to restore their historic houses often go to the Municipal Archives to get images of what the buildings looked like in the 1940s or 1980s.

The same collection is also used by people doing research for film productions, family historians hoping to see what their ancestors’ homes looked like, and scholars trying to measure the transformation of the metropolis over time.

Crime mystery

One popular cache includes photos shot mostly by NYPD detectives, nearly each one a crime mystery just begging to be solved. The black-and-white, top-down image of the two men in the elevator shaft is a representative example.

Although it did not carry a crime scene photo, the New York Tribune reported Nov. 25, 1915, under the headline “Finding of two bodies tells tale of theft,” that the bodies of a black elevator operator and a white engineer of a Manhattan building were found “battered, as though from a long fall.”

The news report said the two men tried to rob a company on the fifth floor of expensive silks, but died in their attempt. The elevator was found with $500 worth of silk inside, stuck between the 10th and 11th floors.

Luc Sante, an author and a professor of writing and photography at Bard College in Annandale-on-Hudson, used images from the police collection for his 1992 book “Evidence.”

“They’re remarkable. They’re brutal. But they are also very beautiful,” he said.

See: The New York City Department of Records archive gallery>