Webb & Knapp

At a glance

Firm: Webb & Knapp, Inc. Principal: William Zeckendorf Sr. (1905–1976), who joined the firm in 1938 and controlled it from 1949 Active: As Zeckendorf's vehicle, roughly 1949 until the firm's bankruptcy in 1965 Focus: Large-scale postwar urban development — Title I slum-clearance housing, mixed-use projects, and towers-in-the-park residential superblocks Signature New York work: Lincoln Towers on the Upper West Side and Kips Bay Towers in Murray Hill — mid-century towers built under the Robert Moses–era urban-renewal program Associated architects: I.M. Pei (Zeckendorf's in-house design head, with James Ingo Freed) at Kips Bay; S.J. Kessler & Sons on the executed Lincoln Towers buildings after Pei's early concepts were value-engineered out Living lineage: Zeckendorf's grandsons, William Lie and Arthur Zeckendorf, carry the family name forward today through Zeckendorf Development Status today: The operating firm is long gone; its buildings survive as prized postwar cooperatives and condops Source: The Roebling Team at Compass — historical and architectural detail verified against The Roebling Research Library, public records, city-planning and academic sources, and published architectural history. July 2026.

Who Webb & Knapp were

Webb & Knapp was the development company through which William Zeckendorf Sr. reshaped a large piece of mid-century New York. Zeckendorf — born in Illinois, raised in New York, and famous as the most audacious dealmaker of his generation — joined the established firm in 1938 and took control of it in 1949, turning a conventional real-estate house into the vehicle for some of the most ambitious urban development the city had seen. He assembled land at enormous scale, worked hand in glove with Robert Moses's Title I slum-clearance program, and thought in whole neighborhoods rather than single buildings.

Zeckendorf's ambition eventually outran his balance sheet: Webb & Knapp went bankrupt in 1965, one of the era's great real-estate collapses. But the buildings endured, and so did the family. Zeckendorf's son, William Zeckendorf Jr., built his own major New York portfolio in the following decades; and his grandsons, William Lie Zeckendorf and Arthur W. Zeckendorf, lead Zeckendorf Development today — the firm behind 15 Central Park West, 50 United Nations Plaza, and 520 Park Avenue. A buyer looking at a Webb & Knapp building is, in a real sense, looking at the first chapter of a development lineage that still shapes the city.

For a buyer, the defining trait of the Webb & Knapp work is scale with a design ambition rarely attached to postwar housing. These were not throwaway rental slabs. Zeckendorf hired serious architects — most notably I.M. Pei, whom he installed as his in-house design director — and the best of the surviving work reflects that.

What they built

Webb & Knapp built the postwar residential superblock: towers set in open, landscaped ground, delivered at neighborhood scale under the federal urban-renewal framework. The firm's two signature New York residential projects sit at opposite ends of that story.

Kips Bay Towers (333 East 30th Street, with its North tower) is the design landmark of the group — I.M. Pei's modernist twin slabs of exposed cast-in-place reinforced concrete, with deeply recessed floor-to-ceiling windows, widely regarded as one of the finest postwar residential buildings in the city and a proving ground for Pei's later career. Lincoln Towers, the eight–building superblock running along West End Avenue near Lincoln Center, is the larger and more conventional project: Pei produced an early master plan, but the executed buildings were designed by S.J. Kessler & Sons after Pei's concepts were value-engineered out on cost grounds — postwar beige-brick slabs on a towers-in-the-park plan, roughly 3,800 apartments across the complex.

What unites the work is the Zeckendorf posture: buy at scale, build big, and — where the budget allowed — reach for real architecture. Most of these buildings began as rentals and converted to cooperative or condop ownership in the 1980s, which is the form in which buyers encounter them today.

Buildings by Webb & Knapp

Webb & Knapp buildings profiled on this site:

• 333 East 30th Street (Kips Bay Towers) — I.M. Pei's modernist reinforced-concrete tower, the design masterpiece of the group
• 140 West End Avenue — the largest of the Lincoln Towers buildings, a 561-unit condop
• 150 West End Avenue — a Lincoln Towers building
• 160 West End Avenue — a Lincoln Towers building
• 165 West End Avenue — a Lincoln Towers building, later owned by the MacArthur Foundation before its 1980s conversion
• 170 West End Avenue — a Lincoln Towers building
• 180 West End Avenue — a Lincoln Towers building
• 185 West End Avenue — a Lincoln Towers building, also formerly MacArthur Foundation–owned
• 205 West End Avenue — a Lincoln Towers building

Beyond New York's residential work, Webb & Knapp's reach under Zeckendorf extended to major mixed-use and urban-renewal projects nationally; the firm's residential legacy in Manhattan, though, is concentrated in the Lincoln Towers and Kips Bay superblocks above.

Track record and market performance

For a postwar developer, the test is whether the buildings hold their standing decades later — and Webb & Knapp's do. Lincoln Towers and Kips Bay Towers remain desirable, liquid, and well-located postwar addresses, and the reasons are structural: large, efficient layouts; light and open exposures on the towers-in-the-park plan; private landscaped grounds; and — at Kips Bay especially — genuine architectural prestige.

The value proposition in these buildings is distinct from prewar co-ops. Buyers come for space, light, protected outlooks, and full-service infrastructure at a relative discount to prewar masonry product, plus, at several Lincoln Towers addresses, utilities-inclusive maintenance and a private multi-acre campus. Kips Bay carries an additional premium for its Pei design pedigree. Across the group, demand has proven durable through cycles, and the postwar co-op / condop format keeps these buildings accessible to a broad buyer pool. For resale, the combination of location, scale, and — at Kips Bay — architectural significance is a real liquidity asset.

Architectural legacy and what a buyer should know

Webb & Knapp's legacy is serious postwar architecture at neighborhood scale, anchored by the I.M. Pei relationship. Kips Bay Towers, though not individually landmarked, is widely regarded as a modernist landmark and one of the most important postwar residential buildings in New York; Lincoln Towers is a defining example of the towers-in-the-park superblock. Neither complex sits in a historic district, so exterior work is not subject to Landmarks review — but the design quality (and, at Kips Bay, the near-landmark status) is part of what a buyer is acquiring.

For a buyer, the honest guidance is that these are 60-to-65-year-old postwar buildings, and they should be bought with that in mind:

• Postwar systems and infrastructure. Buildings of this era carry their own maintenance profile: aging elevators, plumbing risers, window and curtain-wall replacement cycles, garage and plaza waterproofing, and — at Kips Bay's exposed concrete — facade maintenance under the city's periodic inspection program. Many of these systems have been upgraded by the boards over the years; confirm what has been done and what is planned. Ask about recent and upcoming capital projects, assessments, and the reserve fund.
• Renovation scope. Postwar layouts are efficient and generally easier to reconfigure than load-bearing prewar plans, but kitchens and baths in un-renovated lines can be dated, and combinations are still a project subject to the board's alteration agreement. Understand what the building permits before you plan work.
• Ownership structure, board approval, and financials. Several Lincoln Towers buildings are structured as condops — a co-op residential unit inside a condominium wrapper — and trade as co-op shares with proprietary leases and full board approval. Others in the group and Kips Bay have their own conversion histories. Review the offering plan and the specific building's structure, board-approval and financial requirements, sublet and financing policies, and — where relevant — the utilities-inclusive maintenance and land or ground-lease status.
• What to verify. Confirm the reserve fund and any assessments, review recent board minutes for planned capital work, understand the maintenance basis (utilities-inclusive or not) and any flip-tax or sublet rules, and scope the specific apartment's condition. Verify ground-lease or fee-ownership status for the specific building.

None of this is a caution against these buildings — it is ordinary diligence for a well-built postwar tower. Handled well, a Lincoln Towers or Kips Bay apartment is a spacious, well-located, and durable home.

The Roebling Team on Webb & Knapp buildings

We publish developer profiles because the building behind an apartment is part of what a buyer is acquiring — its construction, its board, its place in the market. With a heritage firm like Webb & Knapp, the history is unusually alive: the company that built these towers is gone, but the Zeckendorf name it launched still shapes New York through Zeckendorf Development today. The Roebling Team at Compass tracks Manhattan's postwar and prewar inventory building by building, and we bring that context to every transaction — what the building is, how it has held value, and what to verify before you sign.

If you're evaluating a Lincoln Towers or Kips Bay apartment — or weighing one postwar building against another — a 30-minute consultation is the right starting point.

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Corey Cohen, Principal · The Roebling Team at Compass 646.939.7375 · c.cohen@compass.com

This developer profile reflects publicly available historical and architectural information — including NYC public records, city-planning and academic sources, and published architectural history — together with The Roebling Team's transaction experience. It is provided for research purposes and is not legal advice. The Roebling Team at Compass does not represent Webb & Knapp or its successors, and references to Zeckendorf Development are provided for lineage context only. © 2026 The Roebling Team at Compass.