Architects Michael Arad and Peter Walker designed the 9/11 Memorial. Their proposal, called Reflecting Absence, consists of two reflecting pools that sit in the footprints of the South and North Towers. They're fed by waterfalls (the largest manmade waterfalls in the United States) and surrounded by a forest of nearly 400 trees.
The accompanying 9/11 Museum has an exhibition divided into three sections, the Day of 9/11, Before 9/11, and After 9/11. It uses artifacts, photos, and an extensively researched and well laid out collection to show how the events of 9/11 changed the world.
Designed by architectural firm Skidmore, Owings & Merrill - who also designed the Burj Khalifa - One World is the tallest building in the Western Hemisphere and the sixth tallest building in the world.
The One World Observatory - located on the 100th, 101st and 102nd floors - doesn’t stop bringing the 'wow'; from the moment you enter the building, to its elevator rides, all the way up to the top of New York City.