The original 'Mamma Mia!' film, starring Meryl Streep and based on the ABBA musical, was released, paving the way for the sequel.
Key casting decisions were made including Lily James as young Donna, Amanda Seyfried reprising her role as Sophie, and Cher joining the cast.
Principal photography began on the sequel in locations including Croatia and Greece.
The sequel 'Mamma Mia! Here We Go Again' was released in theatres worldwide.