This year's event takes place from August 4 to the end of September - beginning four days before the Olympic opening ceremony in BeijingPhotograph: AFPThe event is on an even bigger scale than the Olympic opening ceremony, with 120,000 participants performing in unisonPhotograph: Stringer/AFPThe field of the giant May Day stadium is filled with 100,000 dancers and gymnastsPhotograph: AFPSome of the performance is based on traditional Korean culture - Arirang is a popular traditional folk songPhotograph: AFPHowever, the mass games are also devoted to venerating the North Korean regime, including the country's late leader, Kim Il-SungPhotograph: AFPThe pictures are formed by 20,000 people on one side of the stadium, flipping cards in unisonPhotograph: Jonathan Watts/GuardianThe composite card pictures often spell out propaganda messagesPhotograph: GettyThe militaristic theme is also reflected in some of the dancingPhotograph: AFPThe card pictures can be incredibly detailed - and some are even made to movePhotograph: GettyJust over 2,000 non-Chinese foreign tourists visited North Korea last year, with the mass games a key attractionPhotograph: Jonathan Watts/GuardianApart from the relatively high cost of tours, visitors thinking of travelling to North Korea must weigh up the moral implications, given the country's human rights record Photograph: Elizabeth Dalziel/AP