Chicago Public Library

The Chicago Public Library (CPL) is the public library system that serves the City of Chicago in the U.S. state of Illinois. It consists of 80 locations, including a central library, two regional libraries, and branches distributed throughout the city's 77 Community Areas.

The American Library Association reports that the library holds 5,721,334 volumes, making it the 9th largest public library in the United States by volumes held, and the 30th largest academic or public library in the United States by volumes held. The Chicago Public Library is the second largest library system in Chicago by volumes held (the largest is the University of Chicago Library). The library is the second largest public library system in the Midwest, after the Detroit Public Library.

More information on the Wikipedia page.

The website is.