Today we remember 9/11.  Six things you may not know about 9/11, the World Trade Center by the numbers and a time line of the day.

1. 20 people were pulled out of the rubble alive. That included two police officers buried for 21 hours and a woman who was on the 64th floor of one tower who was buried for 27 hours.

2. The British lost the second highest number of people. More than 80 nationalities lost at least one life that day, including 67 Britons.

3. The fire burned for more three months. The World Trade Center fire wasn't completely extinguished until December 19, a full 99 days after the attacks.

4. A third building also fell. Seven World Trade Center collapsed at approximately 5:30 that evening. It wasn't directly hit, but but fires and force of the collapse was enough to weaken the structure and it ultimately fell down.

5. One company lost two-thirds of employees. Financial services firm Cantor Fitzgerald lost 658 of its 960 employees. Ten years later, the firm has donated $180 million dollars to the families.

6. The steel from the WTC was sold. About 185 thousand tons of steel was left in the aftermath of the collapse. Much of it has been sold to China and India the rest was kept and used for memorials.

It is kind of impossible to wrap your head around what happened, even ten years later. It's even more brain scrambling when you think of the enormity of the towers. They were built on six acres of property and the two towers were 110 stories a piece. Tower One was 1,368 feet tall. Tower Two 1,362 feet tall. They contained 200 thousand tons of steel. That's enough to build a five foot sidewalk from Washington D.C. to New York City. There were 104 passenger elevators per tower that moved at a rate of 27 feet per second. The towers had 43,600 windows between them both. That's over 600 thousand square feet of glass. The average daily population was roughly 120 thousand. Fifty thousand people worked in the towers and another 70 thousand visited the towers everyday. Luckily (if you want to use that word) because the attacks happened so early in the day, the towers were far from full.

The horrifying sequence of events began at 7:45am (all times are Central) when the first plane smashed into the North Tower. Reports began pouring in that it was a small plane and it was an accident, but at 8:03am we knew it was something more as another plane crashed into the South Tower. At 8:17, the FAA shut down all airports in the New York City area and five minutes later, Port Authority ordered all bridges and tunnels were ordered closed. At 8:30, President George W. Bush addressed the nation from an elementary school in Florida saying that America has come under attack and that we would work quickly to bring the perpetrators to justice. For the first time in history, the FAA shut down all airports in the U.S. at 8:40am. Three minutes later, a plane crashed into the Pentagon which caused a huge fire and a portion of that building also collapsed. All buildings in Washington D.C. were under evacuation including the Capitol and the White House. At 9:05am, the South Tower collapsed. Five minutes later, reports came in that another plane crashed into a field in Pennsylvania. That was the plane we found out later was also hijacked and was suspected to be headed for a target in Washington D.C. Likely, the Capitol or White House. Stories slowly emerged that the passengers and crew aboard Flight 93 staged a revolt against the hijackers and overtook the plane. At 9:28am, the North Tower fell. At 7:30pm that evening, safely back at the White House, President Bush again addressed the nation and reassured Americans that he was committed to bring those responsible for the attacks to justice. On May 2, 2011 at around 1am Pakistan time, the United States military carried out Operation Neptune Spear and invaded Osama bin Laden's compound near Abbottabad, Pakistan and news broke that bin Laden was in fact dead. It may have taken ten years, but we got him.

Here is a CNN flashback video about the building and grand opening of the World Trade Center.