when in Rome do as the Romans do

when in Rome (do as the Romans do)

proverb One should do what is customary or typical in a particular place or setting, especially when one is a tourist. I know you don't normally get relish on your hot dog, but that's the thing here. When in Rome, do as the Romans do. I don't love cotton candy, but we are at a carnival. When in Rome, right?
See also: Roman, Rome
Farlex Dictionary of Idioms.

when in Rome do as the Romans do

Follow local custom, as in Kate said they'd all be wearing shorts or blue jeans to the outdoor wedding, so when in Rome-we'll do the same . This advice allegedly was Saint Ambrose's answer to Saint Augustine when asked whether they should fast on Saturday as Romans did, or not, as in Milan. It appeared in English by about 1530 and remains so well known that it is often shortened, as in the example.
See also: Roman, Rome
The American Heritage® Dictionary of Idioms by Christine Ammer.

when in Rome do as the Romans do

Follow the local customs. This old proverb supposedly comes from St. Ambrose’s answer to St. Monica and her son, St. Augustine, who asked whether they should fast on Saturday as the Romans do, or not, according to Milanese practice. Ambrose replied, “When I am here (in Milan) I do not fast Saturday, when I am in Rome, I fast on Saturday.” This Latin saying was translated into English by the fifteenth century or so and has been repeated ever since.
See also: Roman, Rome
The Dictionary of Clichés by Christine Ammer
See also:
  • as one door closes, another (one) opens
  • as one door closes, another one opens
  • as one door closes, another opens
  • 1FTR
  • give (someone) an inch and (someone) (will) take a mile
  • give (someone) an inch and (someone) (will) take a yard
  • drive (one) out of office
  • force (one) out of office
  • force out of office
  • give (one) (one's) head