Flag raised at Boston Marathon bombing memorial
Media playback is unsupported on your device

Boston marathon bombing: Joe Biden leads tributes a year on

Boston has marked the first anniversary of the deadly bombing at last year's marathon, honouring the dead and lauding the character and strength of the survivors and the city's residents.

US Vice-President Joe Biden led tributes, saying America "will never stand down" to terrorists.

Go to next video: Marathon finish line repainted