With 400 million records sold and an untold fortune reaped from spin-offs such as the musical Mamma Mia! it's no surprise that ABBA have been able to resist the lure of a comeback tour. Not even a rumoured $1bn (€760m) offer could persuade the quartet to reform back in 2000.
What has been the secret of their enduring success? Quite simply, they were -- and remain -- one of the greatest pop groups of all time, with songs that combine beyond-catchy melodies and intelligent, often incredibly wistful lyrics. Even more so than The Beatles, there is hardly a person on the planet who, off the top of their head, couldn't hum the chorus to at least half a dozen of their hits.
In the 1970s, expressing such an opinion could get you kicked out of rock journalism school. ABBA were derided by critics as purveyors of disposable froth. By the time they drifted apart in 1982 , their stock was so low they didn't even think it necessary to formally announce their break-up.
How things have changed. Over the decades, hits such as Mamma Mia, Fernando and The Winner Takes it All have come to be recognised as ageless masterpieces. Speaking to this journalist several years ago, Stephin Merritt of the indie pop group Magnetic Fields, for instance, argued that Abba were culturally far more important than Bob Dylan.
In a recent interview, Brian Eno -- producer of U2 and one of the godfathers of 1970s art-rock -- admitted that he'd always loved Abba. "In the 1970s, no one would admit that they liked Abba. Now it's fine. .. I like Abba. I did then and I didn't admit it. The snobbery of the time wouldn't allow it."
Nowadays, Abba aren't simply a band -- they are a brand. In Ireland alone, half a dozen tribute bands make a living out of recreating their look and music. Globally, Abba nostalgia is a multimillion-euro business. Witness the blockbuster musical Mamma Mia!, which has reaped more than one billion in ticket sales before becoming a hit all over again on screen in 2008.
"ABBA have a purer joy to their music," according to Bono,who invited Benny and Bjorn to join him on a rendition of Dancing Queen at a 1992 U2 concert in Stockholm. "That's what makes them extraordinary."