In a ceremony on Thursday in the centre of the northern English city where Lennon was born and raised, fans and officials will create a shrine beneath a statue of the legendary Beatle, gunned down in New York by a fan in the presence of his wife Yoko Ono.
Later in the day, the city holds a memorial service for the man who created some of the best-known tunes in pop and is considered one of the most influential songwriters of all time.
The focus then shifts to New York, where Lennon was living at the time of his murder, aged 40.
Friends in Liverpool remembered Lennon with fondness, but also felt he distanced himself from them after meeting Ono, the woman who many fans blame for breaking up the Beatles in 1970.
"You couldn't approach John at the end, and looking back it was from the moment ... he met Yoko Ono," said former friend and fellow musician Billy Kinsley, who knew Beatles Lennon and Paul McCartney in the 1960s.
"It was sad. He was my hero from when I was a 15-year-old kid, and he was always approachable, always said hello, and had a little chat. But after he met Yoko, that went out the window completely."
Kinsley will perform Beautiful Boy, which Lennon dedicated to his second son Sean on his Double Fantasy album, at a memorial service in Liverpool later on Thursday.
In New York, mourners will gather in Central Park and light candles at the time when Lennon was shot.