'Belgravia' is used to refer to the fashionable residential section in any city. It is a very good place to live. It generally implies opulence and happy people, and high property values.
The original Balgravia is the a fashionable residential district of Westminster (southwest London, England) centered on Belgrave Square. It is next to Hyde Park and Knightsbridge. It was originally laid out in the 1820s, and by the 1840s it had entered the language as a descriptive noun.