The design, called the "Phare" (beacon), was declared the winner of the architectural contest on Friday 24 November. At 300 metres high, the 68-storey tower will be slightly shorted than the 320m Eiffel Tower when it is completed in 2012.
Morphosis describe the building as a "hybridized tower" rather than a pure office block as it contains public spaces including a 60m-high atrium, gardens, cafes, shops plus an observation deck and sky restaurant. The building's lower levels provide pedestrian links between an underground transport hub and the surrounding area.
The building contains "sustainable" technologies including a wind farm on the top and a curving facade designed to minimise solar overheating.
"There's a fluidity, a sensuousness, a softness to the form as it reaches to the sky," Mayne says. "Moving around the tower, it appears to shift continually, distinct from different vantage points-not a single image, but a dynamic structure that responds to its site, environment, and performance requirements."
It will be the first architecturally significant new tall building in Paris since the 110m-high La Grande Arche, designed by Danish architect Johann Otto von Spreckelsen and completed in 1990.