There are many synonyms that can be used to replace the phrase "old days". Some alternatives include "days of yore", "days gone by", "days of old", "bygone days", "ancient times", "the past", "historical times", "days of antiquity", and "former times". Each of these expressions carries with it a sense of nostalgia for a bygone era, a time that is now seen as distant and perhaps even romanticized in comparison to the present day. Whether used in a wistful or a critical context, these synonyms all signal a departure from the world as it exists today, a world that is viewed as fundamentally different from the one that preceded it.