It's hard to believe it has been 13 years since the terrorist attacks on the World Trade Centre, which became commonly known as the '9/11' attacks.
New Yorkers are a pretty incredible bunch, and have been sharing images on Twitter that speak louder than words ever could.
— Gary Hershorn (@GaryHershorn) September 11, 2014
Missing. 13 years. #9/11 pic.twitter.com/qk2ksQJPrE
— Helen O'Rahilly (@HelenORahilly) September 11, 2014