Yesterday, with the raising of its mast, One World Trade Center—the "Freedom Tower"—symbolically kicked bin Laden's dead ass by reaching a soaring, magnificent 1,776 feet into the sky. Sort of. Probably.

Measuring the height of a building presents a few problems. Which point on the ground do you use as your basis? Which point on the structure to you call the top? The Council on Tall Buildings and Urban Habitat (CTBUH), the world authority on skyscraper height, has three different metrics: "Height to the Architectural Top," "Highest Occupied Floor," and "Height to Tip." The first of these is the standard by which skyscrapers are judged, and by which One World Trade Center would stake its claim as, at 1,776 feet, "the highest building in the western hemisphere."

But where is its architectural top? According to CTBUH, "architectural top" includes "spires," but not "antennae, signage, flag poles or other functional-technical equipment." Until last year, the designs called for a mast that was fairly unambiguously a spire—a seven-meter wide, architecturally designed element that was clearly part of the building. But in May, to save money, the steel-triangle design was scrapped (over the objections of the architects). What's left is something closer to an antenna than a spire—though CTBUH still hasn't made its ruling (emails to the council went unreturned).

It may not matter, anyway. The 1,776-foot figure bandied about by developers is based on measurements from the center of the building ("we had to pick something," designers told The Observer in 2011). If the CTBUH insists on doing its measurements from "the lowest, significant, open-air, pedestrian entrance," as it says on its website, the height would be either 1,779 feet or 1,787 feet, depending on the placement of the beacon on top of the mast.

And that's not even considering fluctuations in the building itself. Not only will it settle as actual people move in and furnish their offices, the mast itself is likely to change length. "Masts are often designed to allow sway and contraction and expansion to reduce stresses due to rigidity," architect (and co-proprietor of the inspirational web site Cryptome) John Young told us. Even assuming that the designers had done extensive calculation, "a one-foot metric is likely impossible for a structure 1,776 feet tall."

Of course, we're not being entirely fair. Robert Sliman, a structural engineer, told me I was being "picky":

Of course the building moves under both wind load and temperature as well as the variable gravity load inside (called live load), but the height of any structure is usually stated with it being understood that the wind is not blowing and the temperature is some arbitrary value.

But when you wed yourself to symbolism so glib and cloying as that—you have to follow through. If you're going to tell everyone that your new office building rises one foot for every year since the birth of Christ to the signing of the Declaration of Independence, so better to really celebrate Freedom, it better do so. The mythic height 1,776 feet isn't just a "close enough" figure. It's a feat of numerology, a totem clung to by the Lower Manhattan Development Corporation, the Port Authority, and Larry Silverstein through half a dozen designs, two architects, several public squabbles and countless delays.

And every time the wind blows, or it gets hot out, or the ground shifts imperceptibly, it gets less true.