[30] Morgan brought his art collection to the U.S. because an 1897 law allowed him to do it without paying import taxes, and also because he wanted to preserve the objects for the American people.

[35] On the far eastern side of that plot, McKim, Mead & White designed a six-story house at 33 East 36th Street for Morgan's daughter Louisa and her husband Herbert Satterlee.

[62] The Wall Street Journal reported in June 1906 that Morgan had "wanted the most perfect structure that human hands could erect and was willing to pay whatever it cost".

[75][76] During the Panic of 1907, the presidents of the city's banks and trust companies were locked in the library overnight until they agreed on a plan to stop the financial crisis.

[77] To allow people to see his new library from Madison Avenue, Morgan demolished the Dodge house in 1907–1908[14][78] and replaced it with a garden designed by Beatrix Farrand.

[73][98] The import duty exemption expired in April 1915,[99] and Jack sold various items in the collection to pay the inheritance taxes and to raise money for the cash bequests in his father's will.

[135] Officials began raising $3 million for an expansion of the library in 1959; the money was to fund modifications to the annex and a new lecture hall, as well as artifact purchases and new programs.

[156][158] The conservatory would expand the library's space to 45,000 square feet (4,200 m2), add a walled terrace on Madison Avenue, and make the structures wheelchair-accessible.

[195] The renovation cost $4.5 million[194][204] and included cleaning the marble facade, replacing electrical systems and lighting, and opening the North Room to the public.

[239] The Morgan holds original letters by Napoleon, Horace Walpole,[233] Voltaire, Francesco Filelfo,[240] John Cheever,[167] Thomas Pynchon,[167][241] Vincent van Gogh,[242] and George Beaumont.

[147] The music collection includes autographed and annotated libretti and scores from Ludwig van Beethoven, Johannes Brahms, Luigi Cherubini, Frédéric Chopin, Charles Gounod, George Frideric Handel, Joseph Haydn, Gustav Mahler, Gioachino Rossini, and Giuseppe Verdi.

[249] Notable specific pieces include two sets of Schubert's Impromptus manuscripts;[150] Andrea Antico's Motetti e Canzone,[248][146] and Mozart's Haffner Symphony.

[269] The collection also includes numerous drawings from 13th-to-19th-century French masters such as Antoine Watteau, François Boucher, Jacques-Louis David, and Jean Auguste Dominique Ingres.

[264] Other notable artists of the Morgan Library & Museum include Jean de Brunhoff,[271] Paul Cézanne,[272] Gaston Phoebus,[273] and Rembrandt van Rijn.

[279] The Washington Post reported in 1914 that the collections included "tapestries, bronzes and silver, Greek antiques, jeweled miniatures, porcelains, ancient jewelry, and wonderful books and manuscripts".

[286] In 2023, the Morgan and several other institutions surrendered seven pieces painted by Egon Schiele after the New York County District Attorney determined that the works had been looted from the collection of Fritz Grünbaum, who was murdered in the Holocaust.

[43][75][298] The original building occupies a lot of 117 by 50 feet (36 by 15 m)[62][63] and was intended to be built in a similar scale to contemporary New York Public Library branches.

[43][52][299] The exterior walls are made of dry masonry, which allowed the marble blocks to be set evenly, thus requiring a minimal amount of mortar.

[307][308] The lunette panels on the west, east, and south sides of the ceiling, measuring 23 feet (7.0 m) high,[307] allude to material in Morgan's collection.

[321][320] The corner of Madison Avenue and 36th Street contains a two-story Italianate style structure designed by Benjamin Wistar Morris, with space for offices, exhibitions, and a research library.

[91] The Sherman Fairchild Reading Room, the museum's research library, is located on the top floor of the Madison Avenue pavilion[333][334] and has balconies and a skylight.

[57][188] On the south wall of the court is the Clare Eddy Thaw Gallery,[322] a 20-by-20-by-20-foot (6.1 m × 6.1 m × 6.1 m) space inspired by Renaissance chambers that Piano observed in Italy.

[346] A correspondent for the London Times, in 1908, characterized John Pierpont Morgan as "probably the greatest collector of things splendid and beautiful and rare who has ever lived".

[347][60] In 1927, after the library became a research institution, one writer for the New York Herald Tribune called it "a temple of white marble, most fair and proportionate yet with an air of secret exclusiveness".

[297] During the 2000s, a writer for the Chicago Tribune said that, although the Morgan was "a bibliophile's vision of paradise on Earth", it had a lower profile than other New York City museums because of its location.

[303] In 1906, the Real Estate Record and Guide wrote of McKim, Mead & White: "the new Morgan Library, in Thirty-sixth street, is among their most carefully studied designs.

[68][318] Paul Goldberger wrote in 1981 that the main building's facade represented "rigorous, not fanciful, classicism" and the interiors were "very rich and very cold".

Architectural historian Robert A. M. Stern said the 1928 addition "did not frame McKim's jewel box so much as sidle up to it like an unattractive sibling",[104] and Washington Post reporter Benjamin Forgey said it was "not nearly so exquisite" as the original structure.

[298] Goldberger described the Garden Court in 1991 as having "a sleek, almost brittle quality",[159] and Forgey described the conservatory as helping create "a definable low-rise historical place in high-rise New York".

[332] The Financial Times wrote that the 2006 annex's "luminous steel and glass spaces, was as radically different to the heavy stone and dense ornament of the library as was possible".