NEW YORK (AP) — Americans are commemorating the 25th anniversary of 9/11, remembering the shock, the dead and the sweeping consequences of the al-Qaida attacks on symbols of US might and prosperity. Friday’s milestone anniversary brings memorial rituals — wreath-laying, flag-flying, moments of silence, vigils and readings of victims’ names — and volunteer projects in tribute to a day that about half of US adults remember as the most historic event of their lifetime, according to a new poll.

The 2001 attacks unfolded across New York, Virginia, and Pennsylvania, killing nearly 3,000 people and permanently changing American life.

Marking 25 years since 9/11, this photo feature revisits the attacks, timeline, and human toll that reshaped global history.