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 no purpose-built apartment house replicates. 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. Maintenance reflects the lean staffing model — buyers trading down from full-service avenue co-ops should weigh materially lower carry against package logistics and the absence of staff. 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, curated by The Roebling Team research desk. Apartment-level facts are independently verified before publishing; sale prices reflect the recorded transfer amount at the NYC Department of Finance.

Market read. Most recent trades (2025) cleared a median $1,450/sf across 1 sale. Median listing discount -1.1% over ask.

Sales sourced from NYC Department of Finance recorded transfers (BBL 1-01492-0011) and verified listing data. Apartment-level facts (line, condition, asking-price context) curated and cross-verified by The Roebling Team research desk. 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.

You are buying the mansion, and the mansion's mechanics. Eleven shareholders 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.

Expect boutique-board diligence without big-building bureaucracy. Small UES co-ops of this type typically run conservative on financing and structures but move faster than 100-unit houses. 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. The trade is privacy and low maintenance against full-service convenience. 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.

The block is structurally protected. Metropolitan Museum Historic District designation locks the low streetwall and the museum-block character. Light and quiet here are durable in a way mid-block positions rarely are.

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; the buyer pool for mansion co-ops responds to verifiable history, not adjectives.

Comp against mansion conversions, not apartment houses. Building-average and corridor $/sf figures undersell 45-foot-wide mansion geometry. The right comparables are other Fifth/Madison mansion-conversion co-ops, and we maintain that dataset.

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 — clean answers protect the price.

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