The biggest party in the world is under way as Rio de Janeiro's mayor handed over the key to the city to its Carnival monarch on Friday, opening King Momo's five-day reign over the festivities. Taking ...

Carnival King Momo, Kaio Mackenzie, right, with Queen Thuane de Oliveira, hold up the keys of the city from Mayor Eduardo Paes, center, at a ceremony officially kicking off Carnival in Rio de Janeiro, ...