Bono in front of Hansa Studios

Bono in front of the Hansa Studios/Meistersaal in Berlin on 3rd May 2011 as he walks into the building for a film scene and stopping by to say hello to some fans. Probably they're filming for some bonus material for the upcoming 20th anniversary Edition of Achtung Baby. Both happened around 5pm¨. - U2gigs.com

Bono's marriage has 'ups and downs'

Speaking on radio in South Africa, Bono said that the secret to their long union was that Ali is a "very patient missus", the Irish Daily Star reports.

Bono said: "Ali is an incredible person. I'm a 'wherever I lay my hat that's my home' kind of person, but she introduced me to the concept of home.

"I didn't really feel that strongly as a kid, so I owe her that sense of belonging. I hold on to her very tightly, but you have your ups in downs . This is not Mills and Boon territory."

The couple, who met in school, got married in 1982 and have four children together - Jordan, Memphis Eve, Elijah and John.

Bono also spoke about "having nervous dreams" about his children.

"I had mad dreams last night, they were nervous dreams and they were all about my kids. Those kids are amazing. Eve has a movie coming out with Sean Penn, Jordan's a bit of an activist and an amazing piano player.

"And then there's the two boys - they're just comedians. I love being around them. I have a sense that this next generation is going to be much stronger than us."

Bono: The biggest problem facing the next generation (video)

Bono answers the YouTube World View question, "What do you think is the biggest problem facing the next generation and what should we do about it today?"