Of course time travel is a very fertile field for stories. Do the characters in your fictional world have this ability and, if so, how do they do it? How far back in time can they go and do they resist the obvious temptation to change things? If not, what are the consequences?
Can any of your characters time travel or is it restricted to an elite few (they almost certainly would be elite!)? Equally if time travelling is really a case of exploring history, how is this done in your fictional world? Would there be re-enactments and if so are they similar to ours? What would the differences be?
Is history respected or treated with contempt? Does the old saying that a "nation that forgets its history is destined to re-live it" come true in your settings?
How is time itself handled in your work? Does it follow the same pattern as ours - 24 hours days etc - or are the days, weeks etc given different names and lengths of time to represent them?
There should be some story pointers there!