Despite protests from preservationists, Milstein gutted the Biltmore and converted it into an office building called Bank of America Plaza, which reopened in May 1984.

The public dining rooms were all at ground level; the southern side of the hotel featured retail space, while the northern half was devoted to more upscale eateries.

[15] The Biltmore Room still exists beneath the modern-day 335 Madison Avenue;[17] a grand staircase, dating from the original hotel's construction, leads to 43rd Street.

[15][16] In the 2010s, the room was converted to an entrance for the Long Island Rail Road's Grand Central Madison station as part of the East Side Access project.

[19] According to The New York Times, a passenger arriving at Grand Central "will be able to go directly from his seat in the Pullman to his room in the hotel, not only without having stepped from under cover, but without once having passed beyond what will really be one structure".

[5][7] These spaces were all designed in the Elizabethan style, with oak furnishings; marble and wood floors; and paneled walls and pilasters that reached the ceiling.

[8][12] It had dark-oak furniture and red carpets, upholstery, and window draperies;[7] gold-colored decorations of birds and festoons;[35] and marble walls and pilasters.

[27] The dining room's ceiling contained three glass chandeliers and Elizabethan-style gold-on-white decorations of classical figures in low relief.

[7][34] In the center of the room a gilded clock measuring 2.5 by 4 feet (0.76 by 1.22 m) across was displayed;[36] it consisted of two dials flanked by a pair of sculpted nude figures.

[46] On Vanderbilt Avenue, there was a roof garden along the sixth-story setback, with flower beds, shrubs, grass, a fountain, and shaded walkways.

[48] During the summer months, the hotel's managers could open the windows and convert the ballroom into an open-air loggia;[12][9][34] this was a major amenity for guests before air conditioning became popular.

[29][34] A sample room generally had light-colored walls with white-enameled woodwork; a neutral-colored carpet; cream-colored electric chandeliers; and mahogany bureaus, chairs, dressers, and writing tables.

[55] The New York Central's vice president William J. Wilgus proposed electrifying the line and building a new electric-train terminal underground,[56] a plan that was implemented almost in its entirety.

[64] A 1920 New York Times article stated, "With its hotels, office buildings, apartments and underground Streets it not only is a wonderful railroad terminal, but also a great civic centre.

[72] In March 1912, Warren and Wetmore filed plans with the New York City Department of Buildings for the 26-story hotel, which was projected to cost US$4.5 million.

[90] After a protracted legal battle,[90][91] the New York Supreme Court ordered Warren and Wetmore to pay Stem one percent of the Biltmore's construction cost.

[28] These storefronts were initially leased to tenants in the clothing and textile industries, such as the Gotham Silk Hosiery Company[104] and Edward Gropper Inc.,[105] as well as a drug store.

The work included replacing the guest rooms' decorations, adding automatic elevators, refurbishing the restrooms, and installing mechanical equipment.

[132][133] The New Haven wanted Realty Hotels to start paying rent directly to Grand Central's manager, which would split the profits evenly between the two railroads.

The alliance allowed the three hotels to host a single convention across 4,000 guestrooms, 90 meeting rooms, 15 restaurants, and 50,000 square feet (4,600 m2) of exhibit space.

[142] By then, rail traffic had begun to decline with the beginning of the Jet Age and the construction of the Interstate Highway System, and there was also rising demand for office space in Manhattan.

[185][186] Demolition crews entered the same day and began removing decorations,[185][186][180] boarding up the Madison and Bowman rooms even as other parts of the hotel remained open.

But people have shown a rare persistence this last day or two in pushing their way upstairs at the entrance on Vanderbilt Avenue to where the Grand Central Galleries has been holding its own.

[199][200] Norman Pfeiffer of HHPA said the firm had discovered that further demolition had occurred the previous month, to the extent that "there was nothing left to give you even the beginning of a restoration".

[38][199] The Conservancy had accepted the agreement because a recreation of the rooms inside the office tower would "rightly be perceived by architectural historians and the public at large as resulting in a design that would amount to little more than a caricature.

Paul Milstein estimated that the existing steel frame increased construction costs by 25 percent, but it also allowed him to include 200,000 square feet (19,000 m2) more usable space than a completely new building on the site.

[208] Paul Goldberger criticized the new design, saying, "Now the East Coast headquarters of the Bank of America, this is a bloated, heavy form of glass and polished granite, unrelieved by any of the gracious ornament that made the old Biltmore so beloved a presence.

[213] By the 2010s, the building's tenants included several technology companies, such as Addepar[214] and Facebook Inc.[215] During that decade, city government officials sought to change zoning regulations around Grand Central Terminal as part of the Midtown East rezoning plan.

[226] The hotel was a popular meeting place for college students because of its proximity to Grand Central Terminal,[177][227] as well as to several clubs for Ivy League alumni.

[30] Soon after the Biltmore opened, it began hosting annual events, including New York Hotel Men's Association parties,[232] Old Guard balls,[233] and National Horse Show dinners.