Roman tradition dates the end of the monarchy to 509 BCE, when the last king, Tarquinius Superbus, was driven out after his son's assault on a patrician woman named Lucretia — likely a later foundation myth, though archaeology does place the end of Etruscan kingship at Rome around this time. The Romans would carry the loathing of monarchy for centuries afterwards: *rex* became a dangerous, almost ill-omened word.

In the king's place rose a system of balances. **Two consuls** were elected for a single year, could veto each other and were accountable after office. The **Senate** (about 300 members, sitting for life) directed foreign policy and finance. **Popular assemblies** (the *comitia*) legislated and elected magistrates. In emergencies a *dictator* could be appointed for no more than six months — a title that would be twisted in the 1st century BCE by Sulla and Caesar and so open the door to one-man rule.

The deeper test came from within. Centuries of "conflict of the orders" (*conflictus ordinum*) saw the plebeians (the common citizenry) prise rights from the patricians (the old nobility): the tribunes of the plebs (494 BCE), the Twelve Tables (451 BCE — the first written form of Roman law), and the binding legislative power of the plebeian assembly (287 BCE). Outwardly, Rome conquered Italy (by the 270s), then Carthage (the Punic Wars, 264–146 BCE), then the Greek world. The Republic's success outgrew its design: its legions were no longer citizen-soldiers but long-service professionals loyal to their generals. The civil wars of Sulla, Pompey, Caesar and Octavian in the 1st century BCE eroded the system; the Republic gave way in 27 BCE to Augustus's *principate*.

The institutional legacy remained. "Senatus Populusque Romanus" (SPQR) stayed Rome's official seal long into the imperial age. Consul, senate, veto, dictator, constitution — these words still form the core vocabulary of political life today.