What was a core city important to the formation of an empire?

A core city that played a crucial role in the formation of the Roman Empire was Rome itself. As the capital, it served as the political, cultural, and economic center, facilitating governance and administration across vast territories. The city's strategic location and advanced infrastructure, including roads and aqueducts, allowed for efficient communication and trade, which were vital for the empire's expansion and cohesion. Additionally, Rome's influence on law, architecture, and culture helped integrate diverse peoples within the empire.