On March 16, we celebrate the birthday of the fourth president, James Madison. The Library's third building on Capitol Hill is formally called the James Madison Memorial Building. In 1783 Madison became the first sponsor of the idea of a library for Congress by proposing a list of books that legislators might need in their work. The building is also a memorial to him, as the "father" of the Constitution and the Bill of Rights. In 2001, the Library mounted an exhibition, "Madison's Treasures," in observance of his 250th birthday.

The Library is the keeper of the papers of 23 of the U.S. presidents and has the largest single collection of original Madison documents in existence. "Madison's Treasures" highlights some of the most significant of these documents, including the Madison family tree and his case for religious freedom, often regarded as one of the most important American statements on the relationship of government and religion. Madison is also one of the principal authors of The Federalist, which many people consider to be the most significant work on statecraft and political theory ever written by Americans.