Endymion was the first of many Keats manuscripts purchased by J. Pierpont Morgan, who bought it from the London bookseller J. Pearson & Co. for £770 in 1897. It was one of his earliest acquisitions of a literary manuscript, and it became well known that Morgan was the owner. In 1907, the Associate Editor of The Century Magazine, Robert Underwood Johnson (1853–1937), wrote to Belle Greene asking to obtain photographs of the manuscript for the archives of the Keats-Shelley Memorial House in Rome, which would open in 1909. Greene would visit the house in September 1910.