The site was formerly occupied by residences of the Phelps family, one of which banker J. P. Morgan had purchased in 1880. The Morgan Library was founded in 1906 to house Morgan's private library, which included manuscripts and printed books, as well as his collection of prints and drawings. The main building was constructed between 1902 and 1906 for $1.2 million. The library was made a public institution in 1924 by J. P. Morgan's son John Pierpont Morgan, Jr., in accordance with his father's will, and the annex was constructed in 1928. The glass entrance building was added when Morgan Library & Museum was renovated in 2006.