By Martin Edwards
BBC News, London
A privileged few look down on the Notting Hill Carnival from the exclusive properties which line the streets of this normally tranquil district of west London.
The carnival is one of Europe's largest street festivals
Meanwhile, the rest of the hundreds of thousands take to the streets as the event gets into full swing.
Police estimate that at least half a million revellers from all corners of the globe are enjoying the main day of the two-day street party.
Most commercial premises have closed for the day and taken the precaution of boarding up windows and doors while the rest of the area is transformed, as it is every year, into a cacophony of sound and spectacle.
The streets reverberate to the baseline of sound systems playing everything from drum and bass to 60s garage music, proving an irresistible pull for many revellers who dance carelessly in the streets.
"It's great," said Deep Basu, a 31-year-old consultant from India. "I'm having a really fun time.
"I love it because you meet a lot of people from all over the world."
The sheer scale and size of the event has made it one of Europe's largest street festivals, attracting people from all walks of life.
And the three-mile route has come a long way since its humble beginnings when it was first held in St Pancras Town Hall by the Trinidadian community who yearned for a taste of the Caribbean after settling in the "mother country".
Now in its 43rd year, the Notting Hill Carnival has become a major event, boosting London's economy by £100m, according to organisers.
James Rattray, a 26-year music producer from Acton, west London, hopes the carnival will put some extra change in his pocket too.
He and a friend set up an ad hoc stall outside his house, selling drinks to passers-by.
"I have been doing this for the last three years now," he said.
The carnival was first started by Trinidadians in 1959
"Before that, I would just come here and find myself constantly buying food or drink and spending a lot of money. This way, I can listen to music, have some drink and make money at the same time."
He added: "Carnival to me is about everybody having fun. Whether you're old or young, foreign or British, it doesn't matter."
The message clearly is not lost on Muriel Webber.
The 77-year-old woman has been coming to carnival for the last 30 years after she moved to the area in the 1970s. She now lives in Stratford, east London.
"There was trouble here back in the 70s but that was trouble-makers coming from outside," she said.
"Carnival is a good opportunity for people to let their hair down, have a good time and forget their troubles."