Organizers moved Sunday's final mass Organizers of the World Youth Day (WYD) had to move Sunday's final mass to Copacabana because the original site, a huge field outside Rio in Guaratiba, became a mud field after days of rain. Workers had toiled for months to build a huge stage in Guaratiba, but the site that was dubbed "the field of faith" will remain empty this weekend. World Youth Day is seen as a key test for Rio which will host games of next year's World Cup and the summer Olympics two years later. File images of Guaratiba site