ON THIS DAY: The deaths of almost 3000 innocent people on September 11, 2001 following terrorist attacks on the World Trade Centre left the world shocked and sparked a 'war on terrorism'.
On this day 18 years ago we witnessed an unprecedented attack that changed the world.
Planes crashing into the World Trade Centre still seems unthinkable and it is a moment in history that we take the time to remember every year.
"Alongside firefighters and emergency services workers, we pause and pay our respects to those who we will never forget and we also think of those who are sick now or have since died due to their exposure to hazardous dusts and materials while operating at the site for many months after," a statement released on Wednesday from Fire and Rescue NSW said.
Above is a look back at some of the pictures that shocked the world following the terrorist attacks and below is CNN coverage of the collapse.
