Manhattan's skyline as seen from Jersey City, New Jersey, 23 years after the 9/11 attacks.
Gary Hershorn/Getty Images
- This year marks the 23rd anniversary of the 9/11 attacks.
- The World Trade Center site has become a memorial to the 2,977 lives lost.
- Photos from the last 20 years show how New York City rebuilt ground zero.
Each September, two large beams of light reach into the night sky above Manhattan's Financial District in powerful tribute to the towers that once defined the city's skyline.