The 9/11 Memorial opened on September 11, 2011, the 10th anniversary of the attacks. It is located on the western side of the former World Trade Center complex where the Twin Towers once stood. The Memorial was designed by two architects, Michael Arad and Peter Walker, whose proposal was selected in a design competition out of 5,201 submissions from 63 countries.

The Memorial Plaza surrounds two enormous reflecting pools set within the footprints of the North and South Towers. This is where the towers used to stand. The pools feature 30-foot waterfalls—the largest man-made waterfalls in North America. The water cascades into reflecting pools, finally disappearing into the center voids. The names of people who were killed in the 9/11 attacks in New York, at the Pentagon, and on Flight 93, as well as in the 1993 bombing at the WTC, are etched in bronze around the edges of the pools.

The plaza is lined with cobblestones and has more than 400 swamp white oak trees, creating a space for reflection separate from the sights and sounds of the surrounding city. The trees were selected from within a 500-mile radius of the WTC site, including nurseries located in New York, Pennsylvania, and near Washington, D.C., to symbolize areas impacted on 9/11.