This remarkable collection from the New York Public Library's Digital Gallery has historic photographs of aqueducts, sewers, and other essentials that make up the Big Apple's infrastructure. The collection brings together over 600 images that document mass transit proposals and projects dating from 1867. Visitors can make their way through images of the construction of the Holland Tunnel, the multi-county Catskill Aqueduct system, and so on. Some of these materials come from books such as "Interborough Rapid Transit," which was published in 1904. Visitors can browse around at their leisure, or they can also type in their own search terms, like tunnels, railroads, and dams. The site is rounded by the Related Subjects link, which allows visitors to look through related collections created by the Library's Digital Gallery.