17 East 80th Street (The Warburg Mansion)

Gilbert's facade survives in fine condition — architectural histories note the house as "wonderfully preserved" despite replacement windows and altered entrance doors from its institutional decades. The historic-district designation protects the streetscape: exterior work, including windows and rooftop alterations, runs through Landmarks review.

Inside, the apartments date to the late-1970s conversion rather than the Warburg era — the offering plan describes entirely new units built within the mansion shell, the interiors having already been institutionalized by NYU's classroom-and-office decades. The building distributes roughly one to two apartments per floor across seven levels served by an elevator, with the unit scale running from full-floor-class two- and three-bedroom layouts to smaller upper-floor homes under the dormered roof. Mansion-conversion geometry is the draw: 45 feet of width, oversized window openings, and proportions to compare with the actual plans and dimensions of purpose-built apartments. Condition and layout vary apartment to apartment after four decades of private ownership — evaluate each unit on its own renovation history.

This is a self-service boutique cooperative: no doorman, an elevator, a central laundry room, and superintendent/porter service shared by arrangement with a neighboring building per brokerage records. Compare actual maintenance, assessments and shared-staffing costs with identified full-service alternatives; limited staffing alone does not establish lower carrying costs. The cooperative offering plan is on file in The Roebling Research Library; current financial statements and house rules should be obtained through the managing agent during diligence.

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 (2025) cleared a median $1,450/sf (recorded) across 1 sale. Median listing discount -1.1% over ask.

Sales sourced from NYC Department of Finance recorded transfers (BBL 1-01492-0011). 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.

• Paul M. Warburg — the Kuhn, Loeb & Co. banker and Federal Reserve Board member built the house and lived there until his death in the mansion in 1932, covered by The New York Times

You are buying the mansion, and the mansion's mechanics. Eleven apartments share one elevator, one roof, and one 1908 limestone facade. Reserve funding, recent capital work (roof, facade cycle under FISP, mechanicals), and the shared-staffing arrangement deserve close attorney review — small co-ops distribute capital surprises across few shoulders.

The apartments are 1979, not 1908. The conversion built new units inside the shell; original Warburg-era interiors should not be assumed. What is original is the envelope — and that is what the historic district protects and what the market prices.

Confirm this board’s process. Board timing and financing standards vary by building; confirm this one's current requirements from its application instructions. Prepare the package properly — run the Co-op Board Qualification Calculator before offering — and verify pet, pied-à-terre, and financing posture directly, since little is documented publicly.

No doorman is a feature and a constraint. Assess package handling, privacy and actual carrying costs; no doorman does not by itself establish privacy or low maintenance. Buyers who need staff should look to the avenue houses a block away; buyers who want eleven names on the intercom at this address will not find many alternatives.

Understand the historic-district controls. Metropolitan Museum Historic District designation regulates proposed alterations and construction; it does not guarantee an unchanged streetwall, light or quiet. Inspect the apartment’s current exposure and noise and review nearby proposals.

Lead with provenance, precisely. Gilbert, 1908, Paul Warburg, the Federal Reserve, the NYU Institute of Fine Arts chapter — this is one of the best-documented mansion histories on the museum blocks. Use it with specificity: verifiable history, not adjectives.

Compare the actual mansion-conversion layouts. Use suitable Fifth/Madison conversions and other apartments with adjustments for measured area, width, exposure, condition and costs; neither a building average nor another building type necessarily understates value.

Pre-empt small-building diligence. Buyers' attorneys will probe an 11-unit co-op's financials, reserves, and shared-services arrangement. Assemble the documentation before listing so buyers can review it; complete records do not guarantee the price or outcome.

Mansion tax thresholds shape every deal at this level. Run the Mansion Tax Calculator at the intended ask and understand where buyer offers will cluster.

If you're considering 17 East 80th Street, also evaluate:

• 8 East 83rd Street — boutique co-op on a Fifth/Madison mid-block three streets north; the closest positional peer
• 1009 Fifth Avenue — landmarked pre-war directly opposite the Met; the avenue-frontage step-up
• 45 East 82nd Street — boutique pre-war co-op two blocks north between Madison and Park
• 14 East 90th Street — Carnegie Hill boutique co-op on a Fifth/Madison block; same low-density proposition further north
• 1049 Fifth Avenue — the condo alternative behind the Neue Galerie for buyers who want museum-block scale without a board
• 9 East 79th Street — mansion-scale co-op conversion one block south; the like-for-like mansion comp
• 12 East 80th Street — pre-war neighbor directly across the street
• 33 East 74th Street — the Madison Avenue mansion-assemblage condo conversion; the modern interpretation of the same idea