860 United Nations Plaza

The West tower rises 38 floors in dark curtain-wall glass above the complex's six-story office base, its slab proportioned by two slightly protruding piers on the north and south facades. Apartments carry nine-foot ceilings and the oversized windows that are the complex's defining interior feature; the architecture was always in service of the glass, and the glass is in service of the views. Lower floors (through roughly the 15th) were laid out at three-and-a-half to six rooms; the upper floors carry the larger simplexes, and the top eight floors of the two towers hold the complex's 56 duplexes — gallery-and-curved-staircase layouts, some with wood-burning fireplaces, that constitute the trophy inventory. Combinations across lines are common after six decades, and renovation quality varies widely line to line.

The two cooperatives share an operating plant that has few peers in the city: doormen, concierge, attended elevators, the triple-height lobby over the enclosed garden court, the full-block private driveway with its dedicated 49th Street approach off the FDR, valet garage, fitness center, library, four sundecks, party and game rooms, central laundry, and storage — supported by a staff documented at 46 in management-sourced records (some records cite 53). On-site management runs the complex day to day. Each tower maintains its own board, its own share schedule, and its own policy decisions; buyers should not assume that terms documented for one tower bind the other. The West tower's offering plan and amendments are on file in The Roebling Research Library.

860 and 870 United Nations Plaza are two real buildings and two separate cooperative corporations that share a single tax lot and a single city building number. That is unusual, it is not a data error, and it breaks a great deal of automated analysis.

The whole complex — both residential towers and the six-story commercial office base beneath them — sits on block 1360, lot 7501, BBL 1013607501, condominium no. 2692. PLUTO carries that lot under the address of the office base, 866 United Nations Plaza, classifies it as commercial, and reports zero residential units on it, because the apartments sit inside condominium units rather than on the billing lot. The Department of Buildings carries one building identification number, 1040072, for 860, 866 and 870 alike, and the city's building footprint file records a single structure of roughly 413 feet on the lot. There is no separate BIN for the West tower and none for the East.

Where the two towers do separate is in ACRIS. Recorded instruments distinguish lot 9001 — 860 United Nations Plaza from lot 9002 — 870 United Nations Plaza, the two residential condominium units within the complex, with the office units carried across lots in the 1000s under 866. That is the cleanest line in the public record between the two buildings.

What that means for a buyer. Any valuation model, tax lookup, comparable set or building-level statistic keyed to BBL 1013607501 alone will pool 860, 870 and the commercial base into one record and will produce a number that describes none of them. The same is true of anything keyed to BIN 1040072. Use the ACRIS unit-lot distinction — 9001 for the West tower, 9002 for the East — when the record needs to be tower-specific.

And it means the two cooperatives are genuinely separate. Each tower is its own apartment corporation with its own board, its own share schedule, its own financials and its own policies — the offering plan on file describes the West tower cooperative as owning the volume of air space in which its building is constructed above the base. Terms documented for the East tower do not bind this one. In daily life the two co-ops share the lobby, driveway, staff and amenity stack; on paper they share almost nothing. Your attorney should walk through how taxes, base-building costs and shared-amenity expenses flow into maintenance before you sign. The East tower has its own profile.

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 $1,009/sf (floor-adjusted) across 3 sales. 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 4.7% 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 1-01360-7501). 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.

Understand the shared-lot structure before you fall in love. One tax lot, one BIN, two apartment corporations, and a commercial office base underneath — the offering plan describes the cooperative's interest as the air space its tower occupies. None of this is a defect; all of it is unusual, and your attorney should review how taxes, base-building costs, and shared-amenity expenses flow through maintenance.

The views are structural. The UN grounds across First Avenue cannot be built on, and the river cannot be built across. South- and east-facing lines buy permanence that almost no Midtown glass tower can promise; west-facing lines buy the Midtown skyline. Price the exposure, not the building average.

The policy framework is mid-century-co-op moderate, not Park Avenue strict. 75 percent financing per management-sourced records, pets permitted, subletting with board approval and a documented fee schedule, and a buyer-paid 3 percent flip tax. Verify each term against the West tower's current documents — the towers' policies are similar but not interchangeable. Run the Co-op Board Qualification Calculator before offering.

The buyer-paid flip tax changes your closing math. A 3 percent purchaser-paid transfer fee is uncommon and materially affects total acquisition cost — run it through the Buyer Closing Cost Calculator alongside the mansion tax.

Calibrate the neighborhood honestly. The complex is its own precinct — driveway, garden court, playground and Peter Detmold Park adjacent — but the blocks around the UN are quiet at night and the nearest subways are a real walk west. Buyers who love it love exactly that; spend an evening on the block.

Sell the complex's pedigree, at the West tower's price. Harrison & Abramovitz, the UN adjacency, the Le Corbusier-era site plan, the driveway and lobby sequence — the provenance is identical to the East tower's, and the West tower's relative pricing is the value argument. Market against 870's comparables deliberately.

Lead with the operating plant. The staffing depth, attended elevators, and amenity stack are the daily product here and they survive any buyer's diligence. State the service model plainly in the marketing.

Be precise about what is documented. Policies, fees, and financials should be presented from the building's current documents, not from complex-level lore — the two towers diverge in details, and sophisticated buyers' attorneys will catch imprecision. We provide the offering plan and amendments from the Research Library to serious buyers' counsel.

If you're considering 860 United Nations Plaza, also evaluate:

• 870 United Nations Plaza — the East tower of the same complex; identical architecture, separate cooperative, the deeper press-documented resident register
• 845 United Nations Plaza (Trump World Tower) — the corridor's 2001 condominium alternative across First Avenue, with permissive condo mechanics
• 100 United Nations Plaza — 1986 condominium peer a block north; the mid-scale condo alternative
• 425 East 58th Street (The Sovereign) — Emery Roth & Sons 1974; the closest post-war luxury co-op peer in scale and service
• 400 East 56th Street (Plaza 400) — 1968 post-war co-op peer with a similar full-service program
• 45 Sutton Place South — post-war Sutton Place co-op with river frontage
• 2 Sutton Place South — the pre-war trophy alternative on the river
• 1 Beekman Place — the corridor's old-line pre-war trophy co-op; the prestige step-up