Articles about the lives and habits of millionaires seem to be perennially popular. This article ranks the world's millionaires per square mile in 50 different cities. The top five cities are Geneva, Monaco, San Francisco Bay area, Zurich and Paris. No surprises there. Johannesburg, the only South African city on the list comes in at position number 43, wedged between Moscow and Madrid. Take a look to see the top 50 cities for millionaire density. Every tile represents a square mile and every dot equals one millionaire. To read more, click here.