The Beatles co-founder was shot and killed on Dec. 8, 1980 in front of his Manhattan apartment building.
His killer, Mark David Chapman, is still in prison.
Lennon, who together with Paul McCartney fronted the most influential rock band in history, would have been 75 years old today.
His widow, Yoko Ono, thinks he would have embraced the many changes since his death. She said he would "be on a computer all day and night."