“I hate museums,” the French entrepreneur Édouard Carmignac said in 2018. “I want a living foundation.” Back in the 1980s, when Carmignac was invited to a wedding on the Île de Porquerolles, he found just the sort of spot that could be home to the modern art he was starting to collect. It was a place away from the world, located in the South of France, 15 minutes by boat from Hyères—a small commune an hour west of trendier Saint-Tropez. The remoteness was part of its allure, as was its openness to the elements and the seasons. The estate was owned by the architect Henri Vidal, who had created a villa where a farmhouse once stood.

When Vidal died in 2011, his daughters sold the estate to the Fondation Carmignac. Atalier Barani was hired to enlarge the structure underground, bringing modern inflections—glass ceilings, long light-filled halls— to the Provençal villa.