Jack and Jane Morgan continued to employ da Costa Greene as the librarian, expanding the collection with items in which they were personally interested. In March 1924, the Pierpont Morgan Library was incorporated as a public institution. The Morgans transferred the library's building, and the land under J. P. and Frances Morgan's old residence at 219 Madison Avenue, to the Pierpont Morgan Library. The move came as, despite Jack's opposition, the surrounding stretch of Madison Avenue was being redeveloped as a business street. By 1927, the library was planning to double its area; the old J. P. Morgan residence was being demolished to make way for the annex. The plans called for an expanded two-story Italianate style structure designed by Benjamin Wistar Morris, with space for offices, exhibitions, and a research library. The annex, made of the same Tennessee marble as the original, was completed in 1928. While architectural historian Robert A. M. Stern said the addition "did not frame McKim's jewel box so much as sidle up to it like an unattractive sibling", Norval White and Elliot Willensky thought the annex "modestly defers to its master".