Below is a cool video of the 9/11 Memorial Plaza being erected in the shadow of the new Freedom Tower, from 2004-2011 in downtown Manhattan (via The Atlantic).
Time-lapse is certainly the best way to watch 7 years of construction.
The 9/11 Museum posted this description of the plaza:
The 9/11 Memorial features two enormous waterfalls and reflecting pools, each about an acre in size, set within the footprints of the original twin towers. The Memorial Plaza is one of the most eco-friendly plazas ever constructed. More than 400 trees are planned for the plaza, surrounding the Memorial’s two massive reflecting pools. Its design conveys a spirit of hope and renewal, and creates a contemplative space separate from the usual sights and sounds of a bustling metropolis.