Construction is set to begin on the new floors at One Madison Avenue, a 27-story office tower expansion in Manhattan’s Flatiron District. Designed by Kohn Pedersen Fox for SL Green, the project involves the gut renovation of the existing eight-story building and structural addition above its roof level, bringing the structure up to 1.4 million square feet of Class A office space. The National Pension Service of Korea and Hines are also part of the development team and acquired $1.25 billion in construction financing for the property, which occupies a full block bound by East 23rd and 24th Streets and Madison Avenue and Park Avenue South.
Since our last update in late March, installation of the new floor-to-ceiling windows has nearly concluded on the lower levels and the reinforced concrete core for the new floors has begun to rise above the old parapet.
Below are street-level and above-ground photographs from West 23rd Street that show the concrete and steel rebar steadily forming the core for the upcoming tower. This should continue to rise at a constant pace throughout the summer months, and it’s possible the steel-framed superstructure could begin erection in the coming weeks.
The following photos show the look of the new windows in the podium, which feature a cleaner look than their ornate silver-paneled predecessors.
The project will add 530,000 square feet of office space with floor plates ranging up to 35,000 square feet. The new volume will be clad with floor-to-ceiling windows framing views of Madison Square Park, the Flatiron Building, and the surrounding office and residential skyscrapers. The tenth and 11th floors will feature 22-foot ceiling spans and offer access to an open-air rooftop deck. The rest of the terraces are largely concentrated on top of the podium.
Office amenities at One Madison Avenue include a 15,000-square-foot artisanal food market, a 9,000-square-foot tenant lounge, a three-level fitness center, bicycle storage, and a 13,000-square-foot high-tech event space with a capacity of 800. The closest subways from the property are the R and W trains at the 23rd Street station to the west along Broadway between Eataly NYC Flatiron and Madison Square Park, and the local 6 train to the west along Park Avenue South. IBM is the anchor tenant for the development and will occupy 328,000 square feet across five floors.
YIMBY last announced that One Madison Avenue is expected to be completed by the end of November 2023.