Ancus Marcius, the fourth king of Rome, reigned from 640 BC to 616 BC. He was a descendant of Rome’s second king, Numa Pompilius, being the latter’s grandson through his daughter Pompilia. Marcius ascended the throne following the death of Tullus Hostilius, the third king of Rome, and his rule is often considered notable for its blend of military expansion and efforts to secure Roman traditions. Under Ancus Marcius’s reign, Rome expanded to control the whole area between Lavinium to the south and the settlements of Ficana, Crustumium, and Antemnae in the north. The king founded the port of Ostia at the mouth of the River Tiber, which opened up a new sea route to southern Italy and Greece. He also fortified the Janiculum Hill on the western bank of the Tiber River to protect the city from attacks. Despite his military adventurism, Ancus Marcius also sought to uphold Roman religious and legal traditions inherited from his grandfather, particularly in areas of religious practice and law.<\/p>\n