When Vassar opened in 1865, the library was a mere single room in Main with a collection of only three thousand books. In 1893 Frederick Ferris Thompson, a Vassar trustee, gave the college an extension to Main hall that served as a library until the new Thompson building was completed in 1905 by Mary Clark Thompson as a memorial for her husband. Mrs. Thompson's continuing generosity enabled the library to be enlarged in 1918, and in 1924 her bequest to the College became an endowment for its support.