<human>:  When did the Roman senate first meet?
<bot>: The Roman senate was established by the Roman kings in 509 BC. It was originally made up of two parts: the comitia curiata, which was made up of patricians, and the comitia tributa, which was made up of plebeians. The comitia curiata were the original Roman legislative assembly. They met in the Curia, a building in the Forum Romanum, and they voted on legislation, which was then sent to the comitia tributa for ratification.