Rio de Janeiro's mayor has officially opened what has been described as the biggest party on the planet: the city's Carnival Festival. It's the last big bash before Brazil holds the Football World Cup.

Twelve most important Samba schools are each practising, in secret, their songs and dance routines for this year's carnival.

Al Jazeera's Lucia Newman reports as the frantic last-minute preparations are underway.

Source: Al Jazeera