The Zapruder film of the Kennedy assassination; The Mansell Collection from London; Dahlstrom glass plates of New York and environs from the 1880s; and the entire works left to the collection from LIFE photographers Alfred Eisenstaedt, Gjon Mili, and Nina Leen. These are just some of the things you’ll see in Google Image Search today.
Google claims to have access to over 10 million photos and is in the process of digitizing them. The small portion completed is now online and available for you to use as part of your instruction. Full size images can be downloaded in an almost Flickr-ish type layout. The opening page is divided into decades starting with the 1860s through the 1970s and you can also search by tag or keyword as well as browse through different categories. They illustrate the process with one of their favorites, taken in Paris in 1963 and depicting a group of children at a puppet show.
A pretty sweet setup, expecially if you’re looking for historical images or access to primary sources.