Anni-Frid Lyngstad and Björn Ulvaeus, one half of the legendary Swedish pop group ABBA, made a rare joint appearance last night (Jan. 27) to mark the official opening of Abbaworld - a grandiose interactive exhibition staged at London's Earl's Court venue.

Introduced to the stage by Universal Music Group International chairman and CEO Lucian Grainge, who called the band "incredible ambassadors for our industry" and presented the duo with a plaque commemorating 375 million record sales worldwide, Lyngstad expressed her delight with the Abbaworld show, which is promoted by Live Nation. 

"We've already been through the exhibition and I must say I'm so proud of the team that has worked here and also to be part of what is happening here tonight," she said. "We have been on a journey again, in a way."

Ulvaeus, meanwhile, praised the U.K. - where the band achieved international recognition by winning the Eurovision Song Contest in 1974 - as "the perfect place to start a project like this."

"[It's] very innovative and daring and we feel like pioneers again, like we did with [the theater musical] 'Mamma Mia' and I bet a lot of acts will follow," he went on to say. 

Held at London's Earl's Court venue, the exhibition consists of 25 rooms containing a wide range of video footage, music, costumes and memorabilia from the group's career, along with recreations of the band's studio and original offices.

The heavily hyped interactive elements of the show veer from simple quiz machines to the chance to 'remix' ABBA tracks via digital consoles, although the core attraction, where members of the public can sing along with a 3-D holographic representation of the band, is a dazzling spectacle, which proved highly popular with early audiences.

The exhibition, which has been produced by Stockholm-based Touring Exhibitions, remains at London's Earl's Court venue until Mar. 28. The show is then expected to tour internationally although details are yet to be announced.