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Courtesy of Pei Cobb Freed & Partners
Courtesy of Pei Cobb Freed & Partners

The Helix was the first project I.M. Pei designed for William Zeckendorf, president of Webb & Knapp Real Estate Corp. Frustrated by failed plans to build a 39-story commercial replacement for the Marguery Hotel (the world’s largest), Zeckendorf suggested carving the hotel’s palatial 16-room suites into smaller units as 1-bedroom apartments were in high demand after the war. When Pei explained that such a conversion was impossible, Zeckendorf challenged: “Ieoh Ming, if you can design an apartment building that will expand and contract, you’ve got it made.”

Pei gamely conceived of a 22-story chain of wedge-shaped apartments that spiral up in half-levels around a central core. Mechanical, plumbing and living spaces are organized in concentric rings that radiate out to the building’s full 110-foot diameter. The 800-square-foot apartments open to natural light and views through floor-to-ceiling windows. Large terraces (8 feet x 35 feet) were intended to offer the outdoor pleasures of suburban living in the city, protected from neighbors’ views by the tower’s curvature.

Load-bearing concrete fins separate the residential units and keep them column-free. Each unit could remain open as a large studio or be subdivided with modular partitions virtually at will in a matter of hours. As the apartments step up in 5-foot increments, tenants could annex adjacent vacant units to create duplex, triplex, or larger apartments. The split-level arrangement multiplied expansion possibilities – horizontally, vertically, and also diagonally – without sacrificing space for long corridors or flights of stairs. Only a few internal steps were required for connection. Alternately, residents with reduced needs could surrender excess space to neighbors. Rent would be determined by square footage.

Beyond its unique flexibility, the Helix incorporated recent advances in concrete, mechanical and other building technologies; it was among the first apartment buildings planned around central air conditioning. Construction costs were estimated at $2.5 million (roughly $30 million inflation-adjusted to 2022), about 20% less than conventional alternatives.


Expansion possibilities / Courtesy of Pei Cobb Freed & Partners

Innovative and economical, the Helix was widely celebrated in the national and international press, yet it found little support from conservative bankers, who refused funding. Subsequent efforts to realize the project – in San Francisco, Boston, St. Louis, Lower Manhattan, Havana, Singapore – were unsuccessful.

Design: I.M. Pei; Henry Cobb, modelmaker/collaborator
Webb & Knapp Real Estate Development Corp.