The city-state of Monaco on the Mediterranean coast is having problems finding space for millionaires. Monaco is less than 2 square kilometers in size. It is called the playground of the rich. It is home to a Formula 1 Grand Prix, a famous casino and a luxury harbor. Over 30 per cent of its 38,000 residents are millionaires. House prices are already the highest in the world. The average price is around $100,000 per square meter. City planners say about 2,700 more millionaires are hoping to move there in the next 10 years.

Monaco's Prince Albert II has decided to build more homes. He has OK'd a $2.1 billion project to fill in a large area of the sea with concrete. The area will have a big harbor for yachts, a park and Japanese garden, and 120 luxury waterfront homes. There is a big demand for the new homes. People want the luxury lifestyle and no income tax. Experts are worried the construction will damage sea life and the environment. However, the Prince said he cares about the environment. He said important sea life would be moved to a newly-built reef.