All coverage
Biden embraces message of unity on 9/11 anniversary
By Zeke Miller & Alexandra Jaffe
Biden, former presidents honor heroes, lives lost as nation marks 20th anniversary of 9/11
By minyvonne burke & Rhea Mogul
Biden visits all three attack sites on 20th anniversary of 9/11
By Jeff Mason & Trevor Hunnicutt
US marks 20th anniversary of 9/11: Live updates
By Melissa Macaya, Adrienne Vogt & Fernando Alfonso III