Harvard College Library (Cambridge, MA, est. 1638)

The Harvard College Library, established in 1638 shortly after the founding of Harvard College, is the oldest library system in the United States and one of the largest academic libraries in the world. It originated from the bequest of approximately 400 books from Reverend John Harvard (1607–1638), forming the nucleus of the early collection, much of which was later destroyed in a fire in 1764 and subsequently rebuilt.

Today, the system comprises more than twenty-five libraries, with Widener Library as its principal hub, and holds over 20 million volumes alongside extensive manuscript, photographic, and cartographic collections, spanning hundreds of languages and all major fields of study. Primarily serving the Harvard academic community, it also provides controlled access to researchers and visitors and functions as a major international centre for research and preservation.