A look at the principality on the French Riviera, a haven of the super-rich that is home to almost 10 per cent of the world's billionaires, despite being less than a square mile in area. Hotel Metropole Monte-Carlo general manager Serge Ethuin shows viewers around one of Monaco's most prestigious and ultraluxurious hotels, while estate agent Caroline Olds has a client looking to rent a luxury apartment and buy a property for his daughter.