Science and Nature

In the years after the Twin Towers were destroyed in the Sept. 11, 2001, terrorist attacks, New York leaders vowed to build the country's tallest tower in their place as a show of resilience.

They're about to find out if they succeeded.

Early next month the nonprofit Council on Tall Buildings and Urban Habitat—the accepted arbiter on matters of skyscraper height—is set to determine One World Trade Center's official "architectural" height. The developers of One World Trade, the site's signature tower that's set to open in 2015, say the Skidmore Owings & Merrill LLP-designed building measures 1,776 feet. That would be 325 feet taller than the roof of Chicago's Willis Tower, formerly the Sears Tower.

But the bragging rights to America's tallest tower aren't so straightforward.

At issue is whether the One World Trade's 408-foot steel mast is considered a "spire" that is part of the building's architecture. If it is found to be a structural spire, it counts toward the height; but if it is considered just an antenna, that would leave the building at 1,368 feet, the country's third-tallest, after the Willis Tower, at 1,451 feet, and the Trump International Hotel & Tower Chicago, at 1,389 feet.

The answer is subject to debate. "We are caught between a hard rock and a stone," Antony Wood, the Chicago-based building council's executive director, wrote in an email this month to landlord Douglas Durst, a part-owner of One World Trade.

The email points out that if the council, composed largely of top architects and engineers from around the world, rules in favor of the developer, it will upset a constituency that thinks the issue of defining height by a spire's reach has "got out of control." If it rules against the developer, it will upset "the vast majority of the entire USA public for whom the 1,776 symbolic height is sacred," says the email, which was reviewed by The Wall Street Journal.

The council's guidelines are brief, calling for buildings to be measured to their "architectural top," including spires but not antennas or other functional equipment.

Mr. Durst believes the answer is clear: "Logic and their guidelines dictate clearly that the building is 1,776 feet tall," said Jordan Barowitz, a spokesman for Mr. Durst.

Fueling the debate is a design change made last year. Originally One World Trade's mast was meant to have a geometric white shell. But Mr. Durst and the Port Authority of New York and New Jersey, Mr. Durst's partner, dropped it from the plan over cost and maintenance concerns, leaving a steel structure not designed for public view, ringed by service platforms.

The decision sparked criticism from the building's lead designer, Skidmore's David Childs, who said at the time it was "unfortunate" that the Port Authority removed an "integral part of the building's design." He has since refrained from public comment on the issue, and Skidmore Owings has said it supports Mr. Durst's view.

Some onlookers aren't enamored with the current design. "It looks like it's been bolted on. … It does not look like it's part of the building," Pat Crooks, a tourist from Salt Lake City, said of the spire on Friday. She likes the design of the building, she said, but "the top is disappointing."

But Mr. Durst and the Port Authority say a tall spire was a key component of the design, regardless of its outer shell, and the mast should count toward the height of One World Trade, which was formerly named the Freedom Tower. The spire cost $21 million to build and install, according to the Port Authority, and the building's marketing material advertises One World Trade as the tallest in the Western Hemisphere—a claim that depends on the council ruling in its favor.

The decision also has broader reach than a standard skyscraper given its role in preserving and honoring the memory of those who died on Sept. 11. "The idea of building on this sacred ground the tallest building in the U.S. … is very important," said Joseph Daniels, president of the National September 11 Memorial Museum.

This isn't the first time emotions have run high over building heights. In the late 1990s, the Council on Tall Buildings sparked an uproar among Chicago architectural devotees when it ruled the spires atop Kuala Lumpur's Petronas Towers made them 33 feet taller than the Sears Tower's roof, thus ceding the world's tallest distinction to the new towers. Chicagoans noted that the highest usable floor in the Sears Tower was more than 100 feet higher than that of Petronas's highest floor below the spires.

Since, spires have become commonplace on skyscrapers around the world. And they are getting taller: The tall buildings council recently released a report noting that many account today for more than 30% of the total height, up from less than 10% in the 1970s and 1980s.

Architects at Skidmore Owings are scheduled to travel to Chicago to appear before the council's height committee on Nov. 8 to make their case. Peter Weismantle, an architect and the committee's chairman, says the architects "just have to prove to us that it's been designed."

Mr. Durst is angry with the council for even hesitating on an issue he sees as so clear cut. Mr. Barowitz, the Durst spokesman, said the council's process had become "politicized," and their determination "is being driven by a constituency that is offended by design changes that were necessary to make the spire feasible."

Mr. Wood, of the council, said that characterization was "ridiculous," as the criteria aren't specific enough to produce a clear-cut answer, and he expects a robust and intelligent debate over how to handle the tower's official measurement.

Even if the spire-versus-antenna issue is resolved, the building's height may not officially land at 1,776 feet: The council in 2009 changed its rules requiring building height to be measured from the top to the lowest building entrance. Given a slope on the site, One World Trade has an entrance lower than its main doors, which could put the height at 1,781 feet.