The building, located at the northeast corner of Madison Avenue and 66th Street, is ten stories high.

The Madison Avenue and 66th Street facades are both divided vertically into three bays and are ornamented with details such as band courses, ogee arches, finials, crockets, and tracery.

After Raynes ended his involvement with the building in 1990, Classic Properties took over the remaining unsold co-ops, and it sold the retail space.

[5][9] Prior to the current building's construction, the site at 777 Madison Avenue had been occupied by a four-story stone house and a brick-and-stone church.

[11] A small number of luxury apartments were built nearby before World War I, including the Verona two blocks south.

[18][22] 45 East 66th Street is mostly clad in red brick, with light-colored terracotta details,[13][16] in addition to pieces of blackened mortar.

[16][17] The turret rises the entire height of the building and curves 180 degrees counterclockwise from the northwest to the southeast.

[16] The original entrance was through a stone doorway at the corner of Madison Avenue and 66th Street, surrounded by leaf motifs and flanked by canopied windows.

[5] The original plans for the building called for 41 apartments decorated with hardwood, mosaic, and marble tile.

[14] The ground-story apartments were replaced with commercial storefronts as part of a 1929 renovation; the original entrance was moved from the curved corner to 66th Street at that time.

[19] In early 1906, the firm of Schwartz & Gross was hired to design an 11-story apartment building at Madison Avenue and 66th Street, which was expected to cost $400,000.

[32][33] Parkview Real Estate hired Harde and Short that May to design an apartment building on the site.

[6] 777 Madison Avenue was completed in 1908,[19][14] and the Empire Trust Company lent Parkview Real Estate $115,000 for the property that year.

[46] The building had originally been surrounded by a recessed areaway, but this was infilled in the early 20th century as Madison Avenue became more commercial in character.

[47] Gresham Realty, led by the real-estate investor Alexander Bing, bought 777 Madison Avenue in February 1928.

[14][28] After the commercial space was finished, the Scottish-goods importer MacDougalls of Inverness leased a storefront at the building.

[51] Among the building's residents in the mid-20th century were the singer Morton Downey,[52] the politician Grafton D. Cushing,[53] and the socialite Nelly Régine Beer (the wife of banking magnate Robert de Rothschild).

[54] Most of the apartments remained intact during the Great Depression, but rental income decreased due to temporary rent regulation restrictions imposed during World War II.

[57] The racehorse owner Sigmund Sommer bought 45 East 66th Street in July 1973;[58][59] at the time, the building's residents included United Nations ambassadors and theatrical personalities, who paid up to $2,500 a month.

[58][67] The protesting tenants bet on Sommer's horse, in the hope that they would win $100,000 to hire the elevator operator,[66] although they lost their money.

[72] Afterward, the tenants sought to have the building designated as a city landmark, and they commissioned Christopher Gray to write a report about 45 East 66th Street.

[1] By the early 1980s, the building's retail tenants included the shoe store Botticellino[76] and the jeweler Fred Leighton.

Classic Properties took over the remaining unsold apartments, while the Executive Life Insurance Company became a limited partner in the conversion.

[29] The next year, Mitsui Real Estate Sales bought the building's ground-level retail space from Raines for $14.75 million, or $2,854.65 per square foot ($30,727.2/m2).

[86] Twelve of the building's apartments were still rental units by then, even as the remaining tenants had bought into the co-op offering plan.

[63] The building gained more retail tenants in the late 1990s, including the luxury label Goldpfeil[87] and the Italian shoe boutique Pancaldi.

[88] Friedland Properties bought the retail space for $22.55 million in 2001; it was estimated to be the most costly commercial-real-estate transaction in New York City.

[30][31] At the time, the building's retail tenants included a Charles Jourdan shoe store, as well as David Berk, La Perla, and Fred Leighton.

[90] The LPC approved plans for a penthouse structure atop the building in 2014,[26][91] with a bedroom, bathrooms, and dressing rooms.

[84] When the building was being considered for landmark designation in 1977, the historian Paul Goldberger said the "eccentricity of its lavish detailing and round tower strikes just the right note on bustling Madison Avenue" because the decorations redirected observers' attention upward.