How do expressions of time work in Latin?

The way time is expressed in Latin depends on whether you are trying to describe the time when an event occurred, or how long an event occurred for. You should always start by asking yourself: am I answering the question when, or how long for?If you are trying to explain when something happened, you should put your expression of time in the ablative: Cicero Romam venit tertio die. Cicero came to Rome on the third dayIf you are trying to describe how long something happened for, you should put your expression of time in the accusative: Augustus imperator multos annos fuit. Augustus was emperor for many years.