Here's what we know about U2's fourteenth studio release...
Ever since U2 parachuted their thirteenth studio album Songs on Innocence onto Apple devices around the world in 2014 there's been talk of a second album following.
As shock album drops become the new norm - you can never be sure when the world's biggest artists are going to release their latest material.
On Christmas Day Bono confirmed in a video on the group's Facebook page that Songs of Experience is due to be released in 2017 - but a date is yet to be locked down.
The Dubliner previously said that record would be released in 2016.
"We’re going to get this album out next year; unusually for us, a lot of the songs are done already," he told the Irish Times in September 2015 - the piece even recounts Bono pulling over at the side of the road to play tracks from the upcoming record.
Commenting on the album in 2014, Bono told veteran DJ Dave Fanning, 'I think Songs of Experience will come a lot quicker."
"But to explain the wait: we wanted to keep pushing up the level. We wanted songs that would stand up if you played them on an acoustic guitar or piano... eternal songs, the ones that people hold onto ... these songs are rare, they’re like miracles, and they’re almost impossible. If you hear ‘Every Breaking Wave’ played on a piano, you just fall over. And if it doesn’t move you, you’re either deaf or dead, or you should be."
Album number three (slash fifteen)
Songs Of Ascent has been a 'live topic' in the U2 community since Bono referenced it as the title for a forthcoming album in 2009 when the group released No Line on the Horizon.
It was billed as a sister album to the patchy No Line - but it has never seen the light of day.
Soon after No Line came out the band embarked on its 360 tour. That massive undertaking ran from the summer of 2009 to mid 2011 (with some breaks in between).
It's unclear if this was an early working title for the material that would become Songs of Innocence - or if the group is writing a Songs of ... trilogy which will end with 'Ascent.'
A New York Times feature covering the kick-off of the band's 2015 'Innocence and Experience' tour - reported that the band traveled with a mobile recording studio.
"At the very end of an album you’re at the height of your powers in terms of writing, arranging and performing ... It’s a shame that you have to stop then and start the other phase of what we do, which is playing live. This time we haven’t really stopped. Bono is trying to capitalise on that momentum and that sharpness," The Edge told the US publication.
With the Joshua Tree tour running from May until August 1st - if new material is coming it is likely to be released in the Autumn or Winter - allowing a tour to follow in 2018.
Fansite AtU2.com has compiled a comprehensive list of songs mentioned by the band which are yet to surface, among the most recent are 'Landlady,' "'Red Flag Day,' 'The Morning After Innocence,' and 'Instrument Flying.'