Danny Shea, a New York City Police Officer and military veteran, salutes at the north pool of the Sept 11. Memorial, during 10th anniversary ceremonies at the World Trade Center site, Sunday, Sept.11, 2011, in New York.(AP Photo - David Handschuh, Pool)

AP Photo - David Handschuh, Pool

Danny Shea, a New York City Police Officer and military veteran, salutes at the north pool of the Sept 11. Memorial, during 10th anniversary ceremonies at the World Trade Center site, Sunday, Sept.11, 2011, in New York.

In New York City, Washington, D.C., and around the world people gathered to remember the terrorist attacks of Sept. 11, 2001. The attacks brought down the Twin Towers of the World Trade Center in New York and destroyed a section of the Pentagon, killing nearly 3,000 people. Here, we take a look at a few moments from those tributes.