Depends. Modern boxing started in England, but for a century was more popular in the United States. Several cities have been the center for big boxing matches historically but frequently New York, Philadelphia, Boston, LA, Miami, Detroit, Atlantic City, and Las Vegas. Internationally, places like Monte Carlo, London, Macau, Tokyo, Mannheim, and Hamburg have been hot recently. People love boxing in Mexico and South America too, so maybe Mexico City, and Buenos Aires would be likely spots for popular boxing destinations. At the amateur level Cuba punches way above it's weight. Then places like Kazakhstan or Azerbaijan have almost a monopoly on the top talent.
These are the "workplace" rather than "home" of boxing. People go there for money, nothing else is special about them.