According to a study carried out by Spear's magazine and wealth consultancy company WealthInsight, the tiny principality of Monaco has the highest density of millionaires in the world. Well known for being a playground for the rich and famous, almost a third of its 37,000 population hold net assets of $1 milllion or more (excluding their primary residences). After Monaco, you're most likely to pass a millionaire on the streets of Zurich in Switzerland. 27.34 percent of Zurich's population are millionaires.

Another Swiss city, Geneva, rounds off the top three with a millionaire density of 17.92 percent. The gap between the top three and the rest is quite considerable. New York makes it into fourth place with 4.63 percent while Germany's financial capital, Frankfurt, completes the top five with a density of 3.88%.