The viciousness of the attack prompted protests throughout India and led to tougher laws and special courts to deal with rape.
The family of the 23-year-old woman said they planned a small memorial service to keep her memory alive as long as possible, the BBC reported.
A much larger observance, "to claim back the streets of Delhi," was organized by Swaang, a Mumbai theater-and-protest music group, and Majma, a Delhi cultural group.
Musicians were to perform on a moving stage that would travel the route from a mall where the woman and a male friend watched a movie to the bus stop where they got on a bus to go home and ending at the road crossing where the couple were tossed out of the bus.
The woman was attacked on the bus by six men who also beat her friend.
Four of the attackers were given the death penalty. A fifth was found dead in his prison cell before he could be tried and a sixth attacker, a juvenile, is serving a three-year sentence.
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