A two-floor flexible office flagship has taken shape on Fifth Avenue, bringing 27 private offices, executive lounges and conference space to one of Manhattan's most recognizable blocks. The buildout spans 717 Fifth Avenue in the Plaza District, with views stretching toward Central Park and The Plaza hotel, and two tenants have already signed on before the doors fully opened to the public.
Excelsior by Stark Office Suites completed the build-out of the flagship, according to nyrej.com, which put the space at 17,291 square feet. A high-net-worth family office and a healthcare advisory firm have each leased one of the private offices, the outlet reports, with several additional leases described as underway. The flexible office space was set to officially open on September 1.
Size estimates for the project have varied slightly across trade coverage. Where nyrej.com cites 17,291 square feet, rebusinessonline.com separately reported the workspace at 17,300 square feet, spanning the building's 13th and 14th floors. Either figure puts Excelsior's Fifth Avenue outpost among the more substantial flex-office footprints to open in Midtown this year.
Boutique Design Inside a Landmark Tower
The building itself carries some history: the 26-story tower at 717 Fifth Avenue is also known as the Corning Glass Building, according to Commercial Observer. The outlet reports the property recently underwent a multimillion-dollar renovation that added a new lobby, an 8,000-square-foot amenity center, upgraded elevators and a tenant lounge.
Stark's own marketing for the location describes Excelsior at 717 Fifth Avenue as a distinctly boutique, duplex-style environment, per its website, starkofficesuites.com. The company says the space includes dual private entrances leading into a full-block lobby, along with a dedicated amenity center built specifically for the flagship.
Commercial Observer's reporting on the underlying lease adds some financial context that nyrej.com's completion story does not address. Craig Lemle and Roi Shleifer of Savills represented Stark in the lease negotiations, the same outlet notes, while CBRE represented the undisclosed landlord. Asking rent was more than $100 per square foot, according to a source cited by that publication.
Part of a Broader Expansion
The Fifth Avenue flagship is not Stark's first run at the premium Excelsior concept. Stark's first Excelsior location opened at 825 Third Avenue in 2024, Commercial Observer reports, and the 717 Fifth Avenue lease represented an expansion of that brand. Founded in 2004, Stark serves close to 2,000 businesses, according to the same outlet's account of the company's broader New York footprint.
The timing lines up with a Manhattan office market that has been unusually active. Manhattan recorded 8.2 million square feet of leasing volume in the second quarter of 2026, well above the 2025 quarterly average of 7.7 million square feet, according to Cushman & Wakefield. The borough's overall vacancy rate declined 60 basis points to 19.3% during the same quarter, its lowest level since the third quarter of 2021, the firm reports.
Momentum had already been building earlier in the year. Manhattan office leasing activity reached 11.78 million square feet in the first quarter of 2026, the strongest first quarter since 2014, according to Colliers. The firm also recorded positive quarterly net absorption of 2.00 million square feet and a roughly 30% drop in sublet availability over the prior 12 months, landing at 10.86 million square feet.
Midtown specifically has seen some of the sharpest gains. New leasing in the submarket rose 15.0% quarter over quarter to 5.0 million square feet in the second quarter of 2026, per Cushman & Wakefield, while Midtown's overall vacancy rate fell 60 basis points to a 21-quarter low of 17.7%. Against that backdrop, a boutique flex-office flagship with Central Park views and two tenants already locked in fits a market where space, particularly well-located space, has been getting harder to come by.
