The facade of the original hotel is made of limestone and is divided into three horizontal sections similar to the components of a column, namely a base, shaft, and capital.

[10] Lily Churchill, Dutchess of Marlborough, owned the site at the southwest corner of Fifth Avenue and 55th Street until 1891, when she sold it to William Backhouse Astor Jr. for $55,000.

[15][16] At the end of December 1900, Astor leased the proposed Hotel St. Regis to hotelier Rudolph Haan for 20 years, with options for three 20-year extensions.

[3][5] New York City police commissioner Theodore Roosevelt had introduced Haan to the Astor family shortly before the hotel's development.

[27][28] Even as other commercial developments were being built along the midtown section of Fifth Avenue, concerned locals bought up nearby houses to prevent the construction of similar hotels in the area.

[161] Balsa wished to make the hotel "like a private home", so he began giving flowers, scales, and hangers to female guests.

[196] The work included restoring the interior; adding a bar, cocktail lounge, and tea garden; and replacing mechanical systems.

[254] The hotel was temporarily closed to the public in 2020 due to the COVID-19 pandemic in New York City, and the space was instead used by hospital patients who were not undergoing critical care.

[258] The 18-story French Beaux-Arts style hotel, the tallest in the city when completed, was designed by Trowbridge & Livingston,[13] with interiors by Arnold Constable & Company.

[259] When the hotel was built in the early 1900s, New York City construction codes forbade developers from placing any decorative elements outside their property's lot line.

[264] The hotel's decorations were heavily inspired by natural forms, although the St. Regis's facade contains custom balusters, consoles, keystones, and other ornaments.

The outermost bays contain more ornate windows, which consist of sidelights on either side of each casement, as well as curving brackets and ovals in each transom.

[72] Between the two remaining entrance portals is an elliptical, brass-and-copper doorman's booth with curved windows and a rounded door;[266] it is sometimes described as a "sentry box".

[266] The two outer bays on the Fifth Avenue and 55th Street elevations are flanked by rusticated piers;[261][266][267] this was done to "limit and define the design", according to Architecture magazine.

[3][5] According to a contemporary New York Times article, the service elevators could deliver food from the basement kitchen to the top story within 90 seconds.

[200] Because of the presence of massive column-free spaces on the lower stories, the hotel building's steel framework contains large girders and trusses.

[272][281] The first floor contained a lobby, restaurant, café, palm court, and hotel office; all were decorated with ornate marble paneling.

[198] These included a restaurant named Lespinasse, decorated in white and gold; the Astor Court, a double-height tea room; and Le Petit Salon, a large lounge.

[235] The current Dior Suite includes gray-and-cream Louis XVI style furnishings,[305] spread across a dining room, a bedroom, and one-and-a-half bathrooms.

[304] The Bentley Suite on the 15th floor was completed in 2012[236][306] and contains wooden and leather furnishings, as well as items depicting the luxury carmaker's products.

[308][309] Among the earliest events at the St. Regis Hotel was a 1904 banquet for Japanese Prince Fushimi Sadanaru,[310][311] as well as a dinner dance in honor of then-U.S. president Theodore Roosevelt's niece Corinne Robinson.

[312] The King Cole Room hosted literary personalities such as Michael Arlen, Lucius Beebe, John McClain, and Quentin Reynolds.

[292] By the 1960s, the hotel was frequented by film and theatrical personalities such as Marlene Dietrich, Mary Martin, Joan Fontaine, Leland Hayward, Rex Harrison, and Alfred Hitchcock,[161] as well as Marilyn Monroe.

[313] Guests also included noble families and heads of state, such as former Belgian king Leopold III and his wife Lilian; Italian countess Marina Cicogna; and former Swiss president Max Petitpierre.

[321] A month after the hotel opened, W. F. Dix of Town and Country magazine wrote that the St. Regis was "an extraordinary token of the wealth, good taste and prosperity of the nation".

In 1962, Irene Corbally Kuhn wrote for Town and Country: "When hotels everywhere are going in for plastic longevity and jealously measuring every foot of space for its commercial return, the St. Regis is still selling elegance.

[324] A writer for the Montreal Gazette wrote: "Maxfield Parrish's King Cole mural in the bar looks fresher than ever; and the Watteau rooms on the second floor are worth a snoop.

[222] Describing the hotel's service, Terry Trucco of the Times wrote in 1991 that the St. Regis was, "in short, a wonderful blend of landmark preservation and late-20th-century technology, with dozens of delightful details.

"[201] A Wall Street Journal critic wrote in 2000 that "the St. Regis positively gleams with marble, gilt and crystal" and that the "heavily international clientele has an elegant look, but when enough of the elite set pack in, the popular lobby lounge can be uncomfortable, noisy and smoky.

[335] During that decade, preservationists had proposed designating the St. Regis as a contributing property to a planned historic district along the midtown section of Fifth Avenue.