Mason City Public Library, Public library in Mason City, United States.

Mason City Public Library is a two-story Neoclassical building designed by the Chicago firm Patton & Miller, completed in December 1904 with a veneer of Bedford stone. Dedicated on January 10, 1905, it is considered the finest example of Neoclassical architecture in Mason City. The original Carnegie-funded structure now serves as an office building.

The building opened in 1904 with funding from Andrew Carnegie and was designed by the architectural firm Patton & Miller featuring classical elements. Its design reflects the philanthropist's vision of creating public educational institutions across American cities.

The library's name recalls its Carnegie origins, and the 1905 building's Bedford stone veneer was chosen over local limestone after a public debate. The MacNider family donated 7 acres at Second and Pennsylvania for the 1940 replacement, designed by Holabird & Root. The Denison Room, added in 1961, overlooks the garden and Willow Creek.

The Carnegie building at the original site is now an office building and cannot be visited as a library. The working library, dedicated in January 1940, stands on 7 acres at Second and Pennsylvania donated by the MacNider family. Its Denison Room, finished in 1961, overlooks the garden and Willow Creek, and the west wing dates from 1966.

The 1902 Carnegie grant of $20,000 was $7,000 more than Mason City would normally have received, after local attorney James E. Blythe appealed personally to Andrew Carnegie and his secretary through the help of Senator William B. Allison. The Carnegie building, completed in December 1904, is now an office building and was listed on the National Register of Historic Places in 1989.