Religion in ancient Rome encompasses the ancestral ethnic religion of the city of Rome that the Romans used to define themselves as a people, as well as the adopted religious practices of peoples brought under Roman rule. The Romans thought of themselves as highly religious, and attributed their success as a world power to their collective piety (pietas) in maintaining good relations with the gods. According to legends, most of Rome's religious institutions could be traced to its founders, particularly Numa Pompilius, the Sabine second king of Rome, who negotiated directly with the gods. This...