Dancers pose for a picture on Saturday in Rio. Photo: CFP

Dancers on stilts, bare-chested cowboys, Carmelite nuns and plenty of bare flesh flooded Rio's streets Saturday as revelers cranked up the volume at Brazil's carnival festival.

Residents and tourists cast aside their cares to drink from the joyous cup of carnival, considered the greatest show on Earth according to those who live in the "Marvelous City."

Millions of people were expected to take part in the street parade in Rio, an annual celebration since 1918.

Having partied into the night after carnival "monarch" King Momo declared the five-day party open Friday, party-goers were revved up at dawn, many decked out in the distinctive black and white polka dot outfits emblematic of Rio's oldest street party group Cordao da Bola Preta.

The decibel count was steadily growing by mid-morning, and the air was filled with the distinctive orchestral samba blend of  drums, shakers, bells, colorful beaded gourds and countless guitars.

Other cities also held their own festivities, notably Sao Paulo and the northern city of Recife, where some two million people were expected to join in the revelry.

The Recife parade, which attracted a street party world record 2.5 million people two years ago, occurs every carnival Saturday in the Sao Jose district of the city.

Rio authorities hope up to five million people will enjoy the action through Tuesday and splurge up to $500 million.

AFP