When in Rome, do as the Romans do.
50 useful proverbs all english speakers should know
When you are a visitor somewhere away from home, you should act like everyone else. It is polite to do so, and could keep you from getting into trouble. This proverb is from the ancient days of the Roman Empire when the capital city had visitors from all over the world. Cultures were very different between cities in those times. But while in Rome, one would behave like a Roman, no matter where you came from.