On September 11, 2011 - ten years to the day after the tragic events of 9/11 - the September 11 National Memorial and Museum in New York City was dedicated in an official ceremony. The memorial inhabits a large campus around the original World Trade Center site and features two pools in the Twin Towers' "footprints." Names of all of the victims from the attacks in New York City, at the Pentagon, and aboard United Flight 93, which crashed in Shanksville, Pennsylvania, are inscribed on brass plating that lines the memorial fountains. The names of victims who died in World Trade Center attacks in 1993 are also included in this memorial.
Visiting the 9/11 Memorial is free, but reserved, timed passes are required. The Memorial Museum, built underneath the memorial plaza, opened to the public on May 21, 2014, and features mementos—many heart-wrenching—from the events of September 11.
Located on the Pentagon Reservation, an outdoor area within the Pentagon complex, is the National 9/11 Pentagon Memorial. Officially dedicated in a ceremony on September 11, 2008, the Pentagon Memorial features a series of plank-like benches, each representing one of the 184 men, women, and children who died when American Airlines Flight 77 crashed into the Pentagon. The benches are arranged by age and the direction in which each bench is pointed signifies whether the victim died in the Pentagon or was a passenger or crew member on Flight 77.
The Pentagon Memorial is open 24 hours per day. Admission is free.
Flight 93 National Memorial
Among the features of the Flight 93 memorial is the Wall of Names, which displays the names of the all 40 of the passengers and crew aboard the flight. Flight 93, of course, was the only one of four planes used during the September 11 terrorist attacks to not reach its target - the U.S. Capitol. A mutiny set in motion by a group of brave passengers against the terrorists commandeering the plane led to the terrorists crashing the plane rather than risk being overtaken by the passengers.
Admission to the Flight 93 National Memorial is free.