This day in 1974, Swedish pop group, ABBA, began its first tour of Europe, marking the group’s debut circuit outside their homeland. One of the most commercially successful pop groups in history, ABBA skyrocketed to fame by winning the Eurovision Song Contest of that same year, introducing to the world their now infamous hit “Waterloo.” The beginning of their European tour, which brought them to Denmark, West Germany and Austria, was anything but a success – even forcing the group to cancel a handful of appearances. However, by January of 1975, disco fever swept through Europe and the States, and ABBA was playing to sold out audiences everywhere they went. Mamma Mia!