Remembering Sept. 11

In past years on Sept. 11, 2 columns of lights marked the place where NYC's Twin Towers once stood.

As part of the 9/11 Memorial in New York City, 2 square waterfalls were built on the exact footprints of the Twin Towers. The memorial was dedicated on Sept. 11, 2011, and opened to the public the next day.

Visitors from around the world come to pay their respects and see the progress being made on 1 World Trade Center.

The 9/11 Memorial in NYC honors the nearly 3,000 people who died in the Twin Towers and on the ground, near Shanksville, PA, and at the Pentagon, along with those who died in the World Trade Center bombing in 1993.

US Flags honor the memory of 25-year-old Bryan Bennett, whose name is etched into the rim of the north pool of the 9/11 Memorial. Bennett was one of the 2,606 who died in the World Trade Center attacks; he worked for eSpeed, a company that occupied the North Tower (1 World Trade Center).

One World Trade Center is the lead building of the new World Trade Center complex. The 104-story skyscraper is set to open in 2014, making it the tallest building in the Western Hemisphere. The building will stand on land once occupied by 6 World Trade Center.

Most of the 8-acre NYC memorial opened in September 2011. However, the museum (seen here) is still incomplete. Funding issues brought construction to a halt last fall. Today, work has resumed; the museum is expected to see completion in 2014.

After nearly 10 years of planning and fundraising, the Flight 93 National Memorial near Shanksville, PA, was officially dedicated on Sept. 10, 2011. The first phase of the memorial saw completion with the Wall of Names. The names of all 40 passengers and crew who perished on the flight are etched into the white marble.

New York police officers, firefighters and Port Authority police line up at one of the entrances of the 9/11 Memorial Plaza, during the 10th anniversary ceremony. In all, 343 firefighters (including FDNY fire chaplain Mychal Judge), 23 NYPD officers and 37 Port Authority police officers lost their lives in the Sept. 11 attacks. Roughly 2,000 first responders were also injured that day.

Young visitors pay their respects at the 9/11 memorial outside the Pentagon in Washington, DC.

Each year DC-area residents pay tribute to the victims of the attack on the Pentagon.

Dedicated in 2008, the Pentagon Memorial honors those 184 men and women who died on American Airlines Flight 77 and in the Pentagon itself. Each of the benches displays the name of a victim. They are organized from youngest to oldest, from 3-year-old Dana Falkenberg to 71-year-old John Yamnicky Sr.

The Flight 93 memorial near Shanksville, PA, honors the 40 people who died on the hijacked flight trying to save others. While the memorial was dedicated on the 10th anniversary of the attacks, the work is not yet done: $5 million is still left to be raised.