Fans of John Lennon joined his widow, Yoko Ono, in Iceland to mark what would have been his 67th birthday by unveiling a tower of light in his name.
Ono unveiled the monument in Iceland
Ono lit up the Imagine Peace Tower in Videy island, near Reykjavik, as a choir sang Lennon's 1975 song Imagine.
She was accompanied by her son Sean Lennon, Beatles drummer Ringo Starr and George Harrison's widow Olivia.
"We're all here for Johnny's birthday and the big light," Starr said. "I love the light."
The tower is a beam of light radiating from a wishing well, which is engraved with the words "imagine peace" in 24 languages.
It will be lit each year between Lennon's birthday, 9 October, and the anniversary of his death on 8 December.
Ono, who designed the monument 40 years ago, said: "I got the idea because I just liked the romantic idea of having a building that just appears, emerges once in a while but sometimes it is not seen."
"I consider myself very fortunate to see the dream my husband and I dreamt together become reality," said Ono.
Before the ceremony, the director of Reykjavik's Lennon museum, Hatfort Ingvason, said Ono had chosen Iceland as the venue for the monument because of its peaceful reputation.
"It was importantly positioned between the two superpowers during the Cold War - between the Soviet Union and the United States," he told BBC Radio 5 Live.
"She wanted this tower of light, this peace beacon between the super powers to remind everybody that peace was possible," he added.
Ono, 74, said she had gathered hundreds of thousands of wishes for world peace at art galleries around the world.
The wishes will be stored in capsules and buried on the island, each topped with a tree.
Meanwhile, in New York, fans of the Beatles gathered to mark what would have been Lennon's 67th birthday.
Around 100 fans gathered in an area of the park known as Strawberry Fields and sang many of the band's songs.
Lennon was shot dead by Mark Chapman outside his New York apartment in 1980.