in assasins creed i can not find any objectives!

I've went to every view point in every city..or atleast where it is unlocked.And yet i cannot come across not one actual objective.I visit the bureau and all they say is to complete my mission than come back.I went to all cities and not one is available...HELP!!

Try going to areas that were previously unaccessable. By that, I mean go to locked portions of the city and see if they've been unlocked.