The Swedish pop group ABBA was one of the most successful musical acts of the 1970s. Formed in Stockholm in 1972, the group consisted of Benny Andersson, Björn Ulvaeus, Agnetha Fältskog, and Anni-Frid Lyngstad. They released a string of hit singles, including 'Dancing Queen, ' 'Take a Chance on Me, ' and 'Mamma Mia, ' that topped charts around the world. ABBA's music has endured for decades, inspiring a Broadway musical and a feature film.