750 Third Avenue Office-to-Residential Conversion

The reason most office buildings can’t become apartments is the middle of the floor plate. Bedrooms need windows. A 1950s tower doesn’t care. SL Green’s answer at 750 Third Avenue is to cut the building open.

The $805 million conversion turns a 34-story, 761,384-sq-ft office tower from 1958 into 639 rental apartments, one of the largest single-asset conversions in the current Manhattan wave. Gensler is the architect.

Project Scope

Roughly 25,000 sq ft is being removed from floors 4 through 17 to create a notch facing Third Avenue. That opening drives light and air deep into the plate and makes room for a multistory winter garden. The floor area that comes out gets relocated upward, into added floors above and rooftop amenity space, so the deal economics survive the subtraction.

One notched floor alone yields 38 apartments. Bedrooms go on the perimeter to satisfy light-and-air requirements, bathrooms cluster at the interior core where daylight doesn’t reach, and structural beams disappear inside partition walls.

Interior and lobby demolition started in October 2025. The program includes ground-floor and cellar retail, a fitness center, a membership club, coworking, and about half an acre of outdoor space.

Twenty-five percent of the units are affordable under New York State’s 467-m program, which carries a 90% real estate tax abatement on the as-of-right project.

Why It Matters

Carving a light court out of an occupied structural frame is the expensive version of conversion, and most developers avoid it by accepting deep, dark units or walking away from the building entirely. SL Green ran the numbers the other direction: spend the money on the notch, get rentable bedrooms on floors that would otherwise be unrentable, and recover the lost area vertically.

Whether that pencils outside a 467-m abatement is the open question for everyone watching Midtown East. The abatement is doing real work in this deal.

One note on the record. NYC DOB issued a partial stop-work order in late July 2026 covering structural steel on floors 9 and above, citing welding that didn’t match filed plans. DOB reported no structural distress or public danger and rescinded the order two days later after re-inspection.

Project Team & Details