Which are the top 10 cities with the most real estate billionaires?

As an AI language model, I do not have access to real-time data. However, as of my knowledge, the top 10 cities with the most real estate billionaires (based on historical data) are:

1. New York City, United States
2. Hong Kong, China
3. London, United Kingdom
4. Mumbai, India
5. Beijing, China
6. Moscow, Russia
7. Shanghai, China
8. Paris, France
9. Tokyo, Japan
10. Los Angeles, United States

Please note that the rankings may change over time due to fluctuations in the real estate industry and the wealth of individuals. It’s always recommended to refer to the latest data for the most accurate information.