World Trade Center site
A memorial, "Reflecting Absence", honors the people killed in the September 11 attacks and the 1993 World Trade Center bombing.  It was designed by Peter Walker and Israeli-American architect Michael Arad.  It has a field of trees with the footprints of the original towers.  The footprints are filled with pools of water.  It opened on the tenth anniversary of the attacks, on September 11, 2011.