World Trade Center memorial plaza scheduled to open in 2011 , museum in 2012 . As visitors descend underground into the museum , they 'll see the slurry wall , the bedrock that held back the Hudson River when the towers collapsed . Memorial at Pennsylvania plane crash site also due to open in 2011 . Comment: Watch 9/11 memorials in New York and Washington on CNN.com Live .
World Trade Center memorial plaza scheduled to open in 2011 , museum in 2012 . Memorial at Pennsylvania plane crash site also due to open in 2011 . Comment: Watch 9/11 memorials in New York and Washington on CNN.com Live .