Largest university library
Harvard University Library
21,800,000 total number
United States (Cambridge)

The largest university library -- and the largest library operated by a private institution -- is Harvard University Library (USA), in Cambridge, Massachusetts, which holds a total of 21.8 million catalogued items, including 18.7 million physical items and 3.1 million electronic titles, as of 6 October 2021.

Harvard University Library was founded in 1638 as part of the bequest of clergyman John Harvard, who donated £780 (a sum equal to the annual tax receipts of the Massachusetts Bay Colony at the time) and his 400-volume personal library for the establishment of a "school or college" in Cambridge, Massachusetts. This original library grew to some 15,000 volumes before being destroyed by a fire in 1764. Only those books that were out on loan survived. The collection was rebuilt and continued to outgrow its buildings throughout the 19th and early 20th century. Today the core of the collection is housed in the massive Widener Library on Harvard Yard, but there are another 73 sub-libraries around Cambridge, Massachusetts that house the specialist collections of various other departments (i.e. medical books, legal books).