Beyond the fields of lavender and honey-colored farmhouses, the land that launched a thousand fantasies is also home to another kind of delight: dazzling works of art and architecture by some of the great masters of modernism, from Picasso to Le Corbusier. Gully Wells goes on a treasure hunt.

One summer when I was a young and indolent teenager, I was packed off by my mother to stay for a week or so with some old family friends who lived in a farmhouse in the hills above Antibes on the French Riviera. Monsieur, tall with a wild bush of white hair, was a painter, and Madame, petite with olive-black eyes, was a sculptor.