In the heart of the Arizona desert, in a town he founded and reigns over, Jacques-André Istel has created the center of the world. And the 21-foot-tall pyramid, designated the Official Center of Everything by a county board, is but one of several monuments and buildings that Istel and his wife — sole permanent inhabitants of their town of Felicity — have been building since the 1980s. Istel, who earned his fortune by creating a skydiving empire, is currently focused on an elaborate series of town monuments that map the history of human experience. I do have a sense of responsibility, he said of the project.