The Council on Tall Buildings and Urban Habitat (CTBUH) has declared New York's still-unfinished One World Trade Center to be the tallest building in the USA, and for that matter, the entire western hemisphere. The skyscraper ranks third tallest in the world, behind Mecca's Makkah Royal Clock Tower, which measures some 1,972 ft (601 m) tall, and Dubai's mammoth 2,717 ft (828 m) Burj Khalifa.
In honor of the year that the United States made its Declaration of Independence from Great Britain, the height of the skyscraper is 1,776 ft (541 m), and thus edges out Chicago's 1,451 ft (442 m) Willis Tower – formerly the Sears tower – as the United State's tallest building. CTBUH's decision was not made without controversy, however.
The issue revolves around whether the top section of the One World Trade Center is a true spire (permanent structure), or an antenna (subject to change). If deemed the latter, One World Trade Center would have officially measured "only" 1,368 ft (416 m), thus ruining both the Declaration of Independence theme, and perhaps more importantly, placing it lower than Chicago's Willis Tower.
Following discussions with the designers and time spent studying the drawings and plans, CTBUH was duly satisfied that the top section can indeed be considered a spire, as it was demonstrated to be sufficiently permanent and integral to the design.
Alas, even this didn't put an end to the great height question though, as the waters were further muddied by a minor fourth entrance that sits slightly lower than the main lobby. If measured from this point, the building would surpass the symbolic height of 1,776 ft by almost 6 ft.
This final stumbling block was resolved when CTBUH determined that the fourth entrance was not significant enough to be considered as a measurement point, thus paving the way for the eventual decision that the One World Trade Center absolutely, positively, measures exactly 1,776 ft.
Source: CTBUH
