A Suburban Street Straight Up Into the Sky ?

In fact, the idea of a metropolis vaulted hundreds of feet into the air has beguiled fabulists for nearly 100 years. In the early 20th century, experiments by the Russian avant-garde yielded fanciful visions of airborne cities whose economy of space embodied the Communist faith in the perfectibility of man and his environment.

At the movement's forefront was the architect Lazar Khidekel, a protege of Marc Chagall. But Khidekel (pronounced hee-DEK-el) never built his aeropolis. In the early 1930's, Socialist Realism and its mandate of egalitarian accessibility proscribed the nontraditional designs of the avant-garde. His experimental schemes languished in a drawer.

Seventy years later, Khidekel's son, the Russian-American architect Mark Khidekel, has revived and refined his father's blueprint for the accommodation of a revolutionary society in the unlikeliest of places: ground zero. Mr. Khidekel proposes the structure as a replacement for the World Trade Center. He calls it the Vertical Highway.

The idea is as exhilarating as it is improbable. Giant pillars positioned around the footprints of the Twin Towers rise skyward and support scores of open-air plots that seemingly hang in midair. "The age of sealed boxes is over," Mr. Khidekel said. "The World Trade Center was so rigid and confined. How would you evacuate from there?"

Mr. Khidekel said that three construction systems fortify the Vertical Highway: a standard grid of beams and columns, suspension cables, and a DNA-like spiral of roadways, from which the structure gets its name, forming a kind of fishing net impervious to collapse. Models of the skyscraper are currently on display at the Russian-American Cultural Center in downtown Manhattan. The center, founded by Mr. Khidekel's wife, Regina, in 1998, is an artistic mecca for the Russian émigré community.

Mr. Khidekel imagines the structure as primarily residential (though it could also contain business and cultural facilities). "What is America, after all?" he asked. "An endless highway, with plots of land on either side. This building would realize the ultimate American dream: the free-standing home of suburbia amid the cultural and recreational amenities available only in a large city."

Why does anyone ever agree to live or work on the 100th floor? Because its enclosures make them feel as if they are on the 10th. Mr. Khidekel said that in his open-air structure, the effect would be no different from that of a sprawling balcony on Central Park West.

"We have an historic opportunity to construct something radically new in that wounded place," Mr. Khidekel said. "Not only for its practical advantages, but as evidence of our will to live, our perseverance."