On September,13, 509 BC, the traditional date, the Temple of Jupiter Optimus Maximus on Rome's Capitoline Hill was dedicated on the ides of September. An excerpt from the article:
"Temple in Rome
Around 509 BCE a magnificent temple, shared with Juno and Minerva, was erected on Capitoline Hill in Rome, a place where people could gather and make sacrifices. Aside from a large sculpture of Jupiter, the temple, the grandest of all in Rome, housed the Sibylline books which were the oracles of Rome and were only consulted during moments of crisis. Jupiter was worshipped by many titles: Invictus, Imperator, and Triumphator - titles that represented his supreme importance to Rome in all matters of state life, both in peace and war. After returning from battle, victorious generals would lead a procession called a triumph through the streets of Rome to Jupiter's temple. The general would be dressed in a long, purple robe, carrying a scepter in his right hand, riding in a chariot drawn by four white horses; he was followed by a large mass of citizens, his army, and prisoners of war, the latter of course, in chains. After arriving at the temple, he would make a sacrifice, being sure to donate a portion of his booty to Jupiter, thanking Jupiter for his victory in battle.
To these generals Jupiter represented the fearlessness of the Roman army. However, while he was worshipped by the military, often being viewed as a patron of violence, he was also a political god, conferring legitimacy to both the popular assembly and the Senate. The Senate would not allow a declaration of war without the blessing of Jupiter. He was the patron of oaths and treaties and the punisher of perjurers. No political action was begun or completed without his judgment. The chief games celebrated in September, the Ludi Romani, were observed in his honor."