At the heart of the new design is the Freedom Tower which the architects said would be the world's tallest building.
As originally proposed by Mr Libeskind, it will be 1776 feet (541.4 metres) tall, to commemorate the date of the declaration of independence from Britain.
Libeskind's design which won the competition but did not satisfy SilversteinMr Childs has revised the design to include an unoccupied section at the top, housing broadcast antennae and windmills - which he said could generate 20% of the building's energy.
Thank god. I was worried they might attempt to build yet another monument to American excess. Good thing they restrained themselves.