Herodotus's Histories is probably the best place to start. Maybe 50% of it is accurate, as it was common among historians of the day to create functional exchanges of historical figures to simulate the debate of ideas, such as the Persian Magi debating on the kind of government Persia ought to have, between aristocracy, democracy, and autocracy.
Also, and while it is very very modern, John Green's Crash Course World History (and US history) is a great place to start so you have context when you delve deeper.
