I'm talking about ghettos like the original Venetian ghetto (where the name comes from) and Nazi Germany ghettos.
Which are secluded, walled, parts of cities with restricted travel. Even the original ghetto was closed during nights, there was some specific time that the gates closed - if a Jew wasn't inside he was probably going to get killed in the Venetian streets as free game (this is what they said in a documentary about the ghetto).