World Youth Day was initiated by Pope John Paul II in 1986, and is a youth-oriented Catholic Church event. It is celebrated on a diocesan level annually, and at a week-long international level every two to three years at different locations. The international level events attract hundreds of thousands of youth from almost every country on the planet.  While the event itself celebrates the Catholic faith, the invitation to attend extends to all youth, regardless of religious convictions.

The youth of St. John the Baptist have traveled to such places as Rome, Italy; Toronto, Canada; Cologne, Germany; Sydney, Australia; and Madrid Spain

The next world Youth Day will take place in Rio de Janeiro, Brazil.
Check out their official website: http://www.rio2013.com/en
And Facebook page: https://www.facebook.com/worldyouthday