Monaco is an interesting city-state on the shore of the Mediterranean, surrounded by its neighbour France.
A constitutional monarchy with just over 30,000 inhabitants, Monaco has been ruled by the House of Grimaldi since 1297. Today the country is known for tourism and its casino. The citizens are not allowed to gamble at the casino, but they also do not have to pay any income tax.
Combine the nice climate and scenery with the tax haven and you end up with a playground for the wealthy.
Monaco on Wikipedia