Skateboarding, BMX biking, breakdancing and three-on-three basketball, all associated with the youth market that Olympic planners want to win over, have taken over the 18th-century square arranged around the ancient Obelisk of Luxor, gilded fountains and earnest statuary.
"Today these sports are Olympic. But a few years ago they were not, and young people who were practising these sports, we were not welcome, especially not in this area," said the venue manager Mathieu Collet, who comes from Vanves, in the inner Paris suburbs.
"It was a culture of the suburbs not the centre of the city," he said.
Competition opened Sunday with women's street skateboarding, which nailed the "youth" angle with an all-teenage final eight.
Some 10,000 people bought tickets for the two skateboarding sessions, but with general admission tickets the capacity is 25,000 and on Sunday the attendance was approaching that by mid-afternoon, Collet said.
The site covers nearly all the 19-acre square, one end of the formal Tuileries Gardens and the foot of the Champs Elysees, which the French like to call "the most beautiful avenue in the world".
"It completely changes a familiar place," said Audrey Penfornis, who brought her 17-year-old son Marco to watch the skateboarding.
"The atmosphere is brilliant," she said, suggesting it was a good antidote to the highly divisive recent French elections. "It lifts the morale of the French after a difficult couple of months and shows we can be united."
The spectators wandered into the temporary stands of the BMX and basketball venues to see cyclists rehearse tricks or intra-squad three-on-three scrimmages.
All the arenas have a partly open side. Some with a general admission ticket crowded against a fence, or lined the upper stands of the BMX venue, to glimpse the skateboarding.
The food stands, all operating under the slogan "Veni, Vidi, Veggie", served cuisine heavy on goat cheese and courgettes.
There were DJ sets, breakdancing routines and a street artist spraypainting over the designer Olympic fencing as fans lined up to take selfies in front of the monumental Fluvial Fountain.
Children had a chance to try the sports.
"Cool crowd, young and fun environment for kids," said Peter from Copenhagen, watching his five-year-old daughter Clara taking a skateboarding lesson next to the lavender garden in the Tuileries.
"We wanted to show our three daughters Paris, so we thought why not do it during the Olympics. It's very organised and less crowded."
Skateboarding and Monet
His oldest daughter, 11-year-old Josephine, said she had most enjoyed playing basketball and the pastel colours of the Olympic design.
"It's a brilliant venue where usually there is nothing," said Thierry Saint-Martin from Paris, who had come for the day with 11-year-old Hugo, who was shooting a basketball.
For Hugo the highlights had been the "BMX training and the Coca-Cola".
Those seeking a change of pace could walk up the ramp to the Orangerie museum and buy a ticket to see the Monets.
"Skateboarding and the Water Lilies in one day, that is what Paris wants to promote," said Collet.
Adam Adouni of Street Smiles, a group of French break dancers performing slick routines, said they were less technical than the breakers who will compete nearby.
"It's hard to spin on your head on cobble stones," he said, pointing at Concorde's traffic-worn surface.
Adouni, from the eastern fringes of Paris, accepted Place de la Concorde was "different" in its Olympic guise
"Normally, there are cars," he said.
