Urville is a city of 14 million inhabitants that exists entirely in the mind of Gilles Trehin, a French autistic savant.

Trehin began creating plans at the age of 12, using Lego blocks and model airplanes. Today, at 33, he has drawn extensive maps and landscapes of his creation, as well as inventing a culture and a detailed history going back to the 12th century B.C., when he imagines the city was founded by the Phoenicians.

Today, in Trehin’s mind, Urville is the third largest city in the developed world, behind Tokyo and New York, and boasts 87 cinemas, 42 cabarets, 174 public swimming pools and European offices of I.B.M., Sony, Citybank, Olivetti, and Siemens.

“Imagination is more important than knowledge,” wrote Albert Einstein. “Knowledge is limited. Imagination encircles the world.”