U.S. Marks 20th Anniversary of the Sept. 11 Terrorist Attacks

The world solemnly marked the 20th anniversary of 9/11 on Saturday, remembering the dead, invoking the heroes and taking stock of the aftermath just weeks after the bloody end of the Afghanistan war that was launched in response to the terror attacks.

Victims' relatives and four U.S. presidents paid respects at the sites where hijacked planes killed nearly 3,000 people in the deadliest act of terrorism on American soil.

Others gathered for observances from Portland, Maine, to...