The political system through which Rome governed itself for nearly five centuries — replacing monarchy with elected magistrates, a senate, and popular assemblies — before collapsing under the weight of its own military success into the civil wars that produced the empire, and bequeathing its institutional vocabulary to the founders of every subsequent republic.
The Roman Republic invented the senator, the veto, the consul, the census, and the concept of a republic itself. It conquered the Mediterranean world. Then it destroyed itself — in a century of civil wars that its own institutions could not contain — and became the empire that gave the republic its most lasting form: the myth of the lost republic that all subsequent republics have tried to recover.