Every February more than two million people take to Rio's streets to be part of the Rio Carnival – the biggest such event in the world.

The first carnival was held in 1723. Originally it was a Roman Catholic celebration, of merry-making and eating red meat, before the somber 40 days of lent began, in the run-up to Easter Week.

Now the Carnival is a major tourist attraction.

The Carnival's parades are formed of 'samba schools', whose members are drawn from groups of Rio's neighbourhood who want to take part in the parade. But the Carnival isn't just the parade: parties, shows, beauty contests and celebrations are held across Rio for the full week of the Carnival.

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A reveller from the Alegria da Zona Sul samba school takes part in the annual Carnival parade in Rio de Janeiro's Sambadrome.Pilar Olivares/Reuters
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A reveller from the Alegria da Zona Sul samba school. There are around 200 samba schools in Rio, and competition between them for the best float in the carnival is fierce. Pilar Olivares/Reuters
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A reveller from the Alegria da Zona Sul samba school takes part in the annual Carnival parade in Rio's Sambadrome.Pilar Olivares/Reuters
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The Sambadrome is a tiered exhibition hall where carnival parades pass through. Tickets cost from £35 to £3,500. Pilar Olivares/Reuters
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Revellers from the Academicos de Santa Cruz samba school. Anyone can buy carnival costume from a samba school to take part in the parade: if they have $500 to $1,000 to spare.Pilar Olivares/Reuters
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Carnival masks hang on a window of a house near an annual block party known as 'Ceu na Terra' (Heaven in Earth), one of the many carnival parties to take place in the neighbourhoods of Rio de Janeiro.Ricardo Moraes/Reuters
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Revellers take part in an annual block party known as 'Ceu na Terra' (Heaven in Earth). Rio locals who don't want to spend the week partying, and who can afford it, leave the city for Carnival week.Ricardo Moraes/Reuters
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A reveller from the Unidos de Bangu samba school concentrates before taking part in the Group A category of the annual Carnival parade in Rio de Janeiro's Sambadrome. In the Sambadrome parades, samba schools fight for a place amongst the top 12 schools.Ricardo Moraes/Reuters
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Revellers take part in an annual block party known as 'Carmelitas', one of the many carnival parties to take place in the neighbourhoods of Rio de Janeiro during the carnival.Pilar Olivares/Reuters
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The Rei Momo – Carnival King – Wilson Neto dances during the handing over of the ceremonial key to the city, at Cidade Palace in Rio de Janeiro. The event officially kicks off the 2015 carnival week in Rio.Sergio Moraes/Reuters
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Residents of Mangueira slum watch as a participant attends a beauty contest for transvestites and transsexuals at the entrance of the Glam Gay pre-carnival Ball, in Mangueira samba school.Ricardo Moraes/Reuters
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Residents of Mangueira favela – a shantytown – watch revellers at the entrance of the Glam Gay pre-carnival Ball. Samba schools originated in Rio's favelas.Ricardo Moraes/Reuters
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A girl poses next to a reveller at the entrance of the Glam Gay pre-carnival Ball. Carnival Week is a national holiday in Brazil.Ricardo Moraes/Reuters