The Columbus Metropolitan Library (CML) is a public library system in Franklin County, Ohio, in the Columbus metropolitan area. The library serves an area of 872,000 residents, has a collection of 1,483,433 volumes, and circulates 17,262,267 items per year.

The Main Library of the Columbus Metropolitan Library (CML) system is located in Downtown Columbus, Ohio, United States. The public library is the largest in the library system and holds approximately 300,000 volumes. It includes numerous rooms, including separate spaces for children, teens, an adult reading room, newspaper room, auditorium, gallery, gift shop, and a cafe. The third floor includes a computer lab and houses the Franklin County Genealogical & Historical Society.