David and Ezra Nahmad aren’t household names, but in the art world, they’re legends. Born into a Syrian Jewish family, the brothers moved to Europe in the 1960s and began quietly building one of the largest private art collections in the world.

Today, their trove includes over 4,500 works—from Picasso and Monet to Matisse and Rothko—worth an estimated $3 to $4 billion. They reportedly own more Picassos than anyone else, outside the Picasso family.

Their secret weapon? A high-security, tax-free warehouse near Geneva Airport. It’s not open to the public, but it houses a fortune in canvases—and gives the Nahmads the ability to buy, store, and trade art globally with remarkable ease.

They may rarely grant interviews, but the value and scale of their collection speak volumes.