Paris' Longchamp racecourse hosts one of the world's most famous horse races -- the Prix de l'Arc de Triomphe. The site currently houses two huge grandstands -- side by side -- built in the 1960s. This computer-generated image (and the ones which follow) show how the new design will transform the site when completed.
The existing grandstands at Longchamp are packed in the first weekend of October for the running of the Prix de l'Arc de Triomphe -- the richest flat race on turf in the world.
But for the remainder of the year, the stands remain largely empty -- around 30 race meetings are held annually at Longchamp, attracting just a few thousand spectators each time.
Perrault's new design includes just one grandstand but will be "transparent," he says, affording views both east and west.
"The building has two faces -- one in front of the race and one behind," he says.
"On each plateau you have some services -- clubs, hospitality space, restaurants -- but you can see in all directions," Perrault explains.
"The horse-racing side looks out to the east onto Paris, the Eiffel Tower. To the west, you have the River Seine and very nice landscape, a park."
"The idea is you walk on a different plateau and the view on either side is uninterrupted -- like a fluid promenade," he says.
Some of the building's architectural details will also echo its natural surroundings.
"We have a lot of references to the nature around," Perrault said.
"We designed a handrail with a pattern print like a part of the forest. Also we developed some points in the concrete where we printed the scenes of the wood in the 19th century."
Perrault's design was chosen from a shortlist of six. The renovation plan was agreed by France Galop -- the country's horse racing governing body -- in 2011, but funding issues and doubts over Longchamp's viability as a year-round race venue have delayed construction until now.
The project has an estimated c