By Carlo Dellaverson, NBC News

(NBC) - One World Trade Center — the marquee skyscraper that has spent more than a decade in development and construction amid great political debate — has claimed the mantle of tallest building in the country, staving off a challenge from Chicago's Willis (formerly Sears) Tower, an expert panel of architects has announced.

The Council on Tall Buildings and Urban Habitat, the official arbiters of all things architectural, said Tuesday that the 409-foot antenna atop One WTC counts toward the building's full height.

The decision settles a flurry of debate over whether the spire was integral to the structure's design. The organization does not count "antennae, signage, (or) flag poles" toward buildings' officials heights.

Without the needle, the building stands at a 1,368 feet — rivaling but not eclipsing Willis Tower's 1,451 feet.

The announcement caps a decade of development and debate around the skyscraper at the World Trade Center, the site of the Sept. 11, 2001, terror attacks.

A year after the attacks, former New York Gov. George Pataki announced that the new structure would rise to a symbolic 1,776 feet.

One WTC's design went through various fits and starts over the last decade. At one point, an antenna was added that would have vaulted the building's height to over 2,000 feet, making it the world's tallest at the time.

A ceremonial cornerstone was laid on July 4, 2004, years before any concrete was poured and when the building was still known as the Freedom Tower.

Blueprints changed several more times in the ensuing years before construction began in earnest in 2006. All along, the officials, architects and developers involved in the politically-charged project maintained that the building would, at the very least, be tallest in the country — and therefore, the hemisphere.

But a little-noticed move in 2012 — the developer's decision to scrap the decorative sheathing that would have made the mast integral to the building's design and therefore an unequivocal "spire" — prompted uncertainty over whether the building could still claim the mantle of tallest in the U.S.

The design change would have saved $20 million on a $4 billion structure.

One World Trade Center is expected to open next year with Conde Nast as its main tenant.

Rivalry notwithstanding, Willis Tower and 1 WTC face stiff competition from other corners of the globe. One building under construction in Saudi Arabia is set to stand taller than both buildings if they were stacked on top of one another.

NBC News' Daniel Arkin and The Associated Press contributed to this report.