The Harvard Classics, originally known as Dr. Eliot's Five Foot Shelf, is a 51-volume anthology of classic works from world literature, compiled and edited by Harvard University president Charles W. Eliot and first published in 1909.
Eliot had stated in speeches that the elements of a liberal education could be obtained by spending 15 minutes a day reading from a collection of books that could fit on a five-foot shelf. (Originally he had said a three-foot shelf.) The publisher P. F. Collier and Son saw an opportunity and challenged Eliot to make good on this statement by selecting an appropriate collection of works, and the Harvard Classics was the result.
Eliot worked for one year with William A. Neilson, a professor of English; Eliot determined the works to be included and Neilson selected the specific editions and wrote introductory notes. Each volume had 400-450 pages, and the included texts are "so far as possible, entire works or complete segments of the world's written legacies." The collection was widely advertised by Collier and Son, in Collier's Magazine and elsewhere, with great success.
gutenberg.net, has e-versions and a description of the series:
wikipedia, has a description of the series:
list of downloads optimized for mobile, like Kindle, etc.