When in Rome, do as the Romans do

• ‘When in Rome, do as the Romans do’ is a medieval phrase meaning visitors should follow the local customs.
• The phrase is attributed to Aurelius Ambrose (340-397 CE), the Bishop of Milan under the Emperor Gratian.

Ambrose

• Ambrose was asked to clarify whether Saturday was a fast day, as Milan and Rome observed it on different days.
• His response was that when he was in Milan he did not fast on Saturday, but when he was in Rome he did fast on Saturday.
• This response is thought to have led to the proverb ‘When in Rome, do as the Romans do’ meaning visitors should follow the local customs.