In the late 6th century BCE, the small city-state of Rome overthrew the shackles of monarchy and created a republican government that, in theory if not always in practice, represented the wishes of its citizens. From this basis the city would go on to conquer all of the Italian peninsula and large parts of the Mediterranean world and beyond. The Republic and its institutions of government would endure for five centuries, until, wrecked by civil wars, it would transform into a Principate ruled by emperors. Even then many of the political bodies, notably the Senate, created in the Republican period would endure, albeit with a reduction in power.
This is a companion discussion topic for the original content at https://www.worldhistory.org/Roman_Republic/.