Answer: Senate
Explanation:
The Romans came up with the concept of a Senate which was essentially an assembly of the elders of the Romans. It was first established in the Roman Kingdom where it was mostly powerless as it was an advisory council to the King.
During the years of the Roman Republic however, the Senate became very powerful and began to govern Rome. With the establishment of the Roman empire however, the Senate lost its power once more and never regained it to the extent it was in the Republic.