4W21

Hardy's facade is the building's signature — an articulated skin of glass and stainless steel that catches light and echoes the rhythm of the loft buildings around it, modern but grounded in context. Behind it, the homes deliver the proportions buyers come to the Flatiron for: floor-to-ceiling windows, hardwood floors, and ceiling heights near ten feet.

The 54 residences run from one-bedrooms through three-bedroom homes, with a handful of terraced two-bedrooms and two penthouses crowning the building. Kitchens were finished to a high contemporary specification — high-gloss Italian cabinetry, premium appliances, and stone counters — and the open layouts read as updated lofts. The mix favors two-bedroom homes, with the larger and terraced units and the penthouses commanding the building's strongest pricing.

4W21 operates as a full-service condop with a full-time doorman and resident staff. For a building of its size, the amenity package is genuinely useful: an on-site parking garage — a real rarity in the Flatiron — plus a fitness room, a roof deck, bicycle storage, and private storage.

The condop structure is the operational headline. Because the building is a cooperative that functions with condominium-like flexibility, buyers generally find a lighter approval process and more accommodating rules than at a conventional co-op, while still benefiting from the single, all-in monthly maintenance and the cohesive management a co-op provides. Specific board policies on financing, subletting, pieds-à-terre, and pets follow the building's proprietary lease and house rules; the structure is designed to be more permissive than the pre-war co-op stock nearby. The location — steps from Fifth Avenue with Union Square, Gramercy, Chelsea, and Midtown transit and retail all close — does the rest.

Recent sales

Recent transfers at this building, from The Roebling Research Library. Prices are the transfer amounts recorded with the NYC Department of Finance; apartment-level detail is checked against the building’s own file in The Roebling Research Library before publishing.

Market read. Most recent trades (2026 to date) cleared a median $1,310/sf (floor-adjusted) across 1 sale. Floor-adjusted means each sale is restated to a constant mix of floors, so the figure can differ from the plain median of the sales listed above. Median listing discount 4.2% from the last ask — a recurring negotiation gap worth pricing into any offer or listing strategy.

Sales sourced from NYC Department of Finance recorded transfers (BBL 1-00822-0045). Apartment-level facts (line, condition, asking-price context) curated and cross-verified in The Roebling Research Library. Not all transactions cross-verify with ACRIS records — sponsor and LLC purchases sometimes record at stipulated values rather than market price; square footage on co-ops is not officially recorded, figures shown are approximate.

The first thing to understand is the structure: this is a cooperative operated as a condop, which typically means a lighter approval path and more flexible rules than a traditional co-op while retaining co-op simplicity. City records also show the land under a ground lease (dated 2003, recorded 2005); confirm the ground lease, its amendments and rent schedule with counsel, and include ground rent and any future changes in the carrying-cost analysis. Confirm the building's current posture on financing, subletting, and pieds-à-terre as part of your offer, since those are the levers that distinguish a condop from a standard co-op. Beyond structure, focus diligence on floor and exposure, the layout and whether the home has a terrace, and the scope of any renovation. The on-site garage is a genuine differentiator in this neighborhood and worth weighing. Review the building's financials and the all-in maintenance, and lean into the location — few Flatiron addresses are this central.

Lead with the building's distinct combination: a Hugh Hardy-designed glass-and-steel facade, loft-scale homes with near-ten-foot ceilings, a rare on-site garage and roof deck, and the flexibility of condop ownership — a package the surrounding pre-war co-ops and conventional lofts cannot match. Disclose the ground lease at the outset and have its terms and rent schedule ready for buyers' counsel. Benchmark to comparable Flatiron buildings and emphasize the structure's looser rules to buyers who want condo-like flexibility without condo pricing. Stage to the home's light, ceiling height, and any terrace, and if the sale includes garage access or a deeded space, make it prominent — it is a meaningful draw in this corridor.

If you're considering 4W21, also evaluate these Flatiron and nearby downtown peers:

• 15 West 20th Street — Flatiron luxury building a block south
• 16 West 19th Street — boutique Flatiron building nearby
• 16 West 16th Street — established building to the south
• 100 West 15th Street — full-service Flatiron / Chelsea building
• 101 West 24th Street — modern Chelsea / Flatiron tower