The New York Public Library has digitized over 275,000 images from their collections, and made them freely available online.

The 'NYPL Digital Gallery provides access to over 275,000 images digitized from primary sources and printed rarities in the collections of The New York Public Library, including illuminated manuscripts, historical maps, vintage posters, rare prints and photographs, illustrated books, printed ephemera, and more.

Here is an excerpt from the press release listing some of the categories:

<sub>* Revolutionary War Scenes -- several thousand images from the Thomas Addis Emmet Collection of Illustrations Relating to the American Revolution
* Civil War Photos -- 183 rarely seen photos documenting battlefield medical treatment
* New York City History -- tens of thousands of archival photographs of buildings and streetscapes
* Illuminated Medieval and Renaissance Manuscripts -- more than 2,000 manuscript pages and associated illuminations
* 16th-century Maps of North America -- including the earliest published maps of the continent
* Sheet Music Covers -- from the late 19th and early 20th centuries
* Civil and Mechanical Engineering -- images from the 16th to the 20th century
* Manhattan Pre-War Apartments -- 1,260 floor plans and elevations
* Yiddish Theatre Placards -- from New York and Buenos Aires, 1900s to 1930s
* Animal Illustrations -- 5,000 pages from illustrated classics published in the 17th to 20th century
* Japanese Prints -- 17th- and 18th-century woodcuts
* Fashion Illustrations -- from the 19th to early 20th century
* Menus -- several thousand restaurant menus from 1851 to the 1920s
* Russian Civil War Posters -- 213 posters, placards, and broadsides from 1918 to 1922
* Theatre Photographs -- 1,500 photos from 1900 to 1957 including pictures of Fred Astaire and the Marx Brothers</sub>


Digital Gallery
New York Public Library Press Release