Boston is marking the anniversary of the deadly bombing at last year's marathon, honoring the dead and lauding the character and strength of the survivors and the city's residents.
US Vice-President Joe Biden told survivors they were an example of "pure courage".
The city's leaders thanked those who saved lives in the frenzied aftermath.
Three people were killed and some 264 injured when two bombs exploded near the finish line at last year's race.
"I know that no memorial, no words, no acts can fully provide the solace that your hearts and soul still yearn to acquire," Biden said at a midday memorial programme. "I hope it eases your grief a little bit."
Participants in Tuesday's ceremonies included representatives from families of the victims, members of the city's fire, police and ambulance services, government agencies and civic organizations.
Dignitaries in attendance included Mr Biden, former Mayor Thomas Menino, current Mayor Martin Walsh, Governor Deval Patrick, Senator Elizabeth Warren, and others.
This year's Boston Marathon is due to take place on April 21st.
