In the basements of Bordeaux (2/6): under the water mirror, a space as big as a football pitch

Beneath the world's largest reflecting pool lies an even larger space. This former warehouse and parking lot now houses the water filtering and softening facilities, among other things. Guided tour

C ocorico! Bordeaux is home to the world's largest water mirror: 3,450 square meters, while Nice's measures 3,000 square meters and Washington's, 3,100 square meters. What is little known, however, is that the space underneath is roughly double that . The size of a football field, it is generally said. That is 7,000 square meters. That's not too much to maintain an underground reservoir with a capacity of 800 cubic meters, and machinery that manages more than 900 injectors, the devices that send water onto the slab in the form of tiny droplets.

In any case, this justifies the tourist office's recommendation to visit the place. Those who come there hoping to find some cool air will be disappointed: the temperature is roughly the same as on the surface. On the other hand, those who want to know more about one of Bordeaux's most attractive sites – which attracts several million visitors each year – will find answers. And a change of scenery.

Located opposite the Customs Museum, the access staircase leads to a former underground warehouse, built between the two world wars. "We didn't build it on the surface, unlike the hangars on the Quai des Chartrons, because we already felt it was necessary to clear the view overlooking the Place de la Bourse, considered the most beautiful square in Bordeaux," explains Catherine Goniak, a tour guide at the tourist office.

“When you filter the water, you find everything: toys, inflatable balls, broken bottles, hotel cards…”

The Art Deco style of the 1920s and 1930s can be seen in octagonal openings, which were once light wells, or in elegant pillars that support the ceiling. "At the time, people liked buildings to be beautiful, even for a simple warehouse."

A huge "floushhhhh" echoes. "It's the water from the mirror emptying into the basin," explains Guillaume Gregeois, one of the technicians who maintains the facility. That means softening the water to preserve the pipes—and protect the skin of those wading on the slab above—and filtering the water when it reaches the basement. It's no small feat. "We find everything: toys, inflatable balls, broken bottles, hotel cards... Not to mention the time some farmers dumped slurry . It took us ten days to clean everything up."

But the walk also reveals markings on the ground – when the warehouse ceased to function, the place was a parking lot –, the piping of the fountain that once stood on Place Marie-Brizard – why and until when is it there? No one can answer –, and even a bunker dating from the Second World War built to store and protect equipment, not for defense purposes.

And ultimately, this joyful hodgepodge logically reflects the purpose of the water mirror. Originally, urban landscape designer Michel Corajoud envisioned it as a way to enhance the majestic façade of the Place de la Bourse. But it quickly became a space of freshness, well-being, and conviviality, disconnected from its landscape dimension. "A work of art belongs to those who bring it to life," smiles Catherine Goniak.