Five years on from the event that has shaped the early twenty-first century, we want to hear your stories. Were you in New York on that day? Do you know people who were caught up in events?
Wherever you are in the world, we want to know how you feel life has changed in the last half-decade.
You can also send pictures to: [email protected]
The best of the material that you send us will be showcased on the site - this is your chance to share your stories with the world.
Where were you that day? How has the world changed? Five years on, how has your life changed? Send us your stories using the form below.
We will be discussing America and the World Since 9/11 in two special editions of our global phone-in programme Have Your Say on Saturday 9 September at 1700 GMT and Sunday 10 September at 1400 GMT. If you would like to take part please send us your telephone number. This will not be published.
You can send pictures and video to: [email protected] or to send via MMS please dial +44 (0)7725 100 100. Do not endanger yourself or others, take any unnecessary risks or infringe any laws.
You can also text your thoughts to: +44 7624 800 100
The BBC may edit your comments and cannot guarantee that all emails will be published.