Cities built throughout the roman empire modeled their urban planning on what city?

Romans preferred a much more regular, rational layout and plan. They inherited the Greek tradition of city planning on rectangular grids but they refined it to include more open space and central public focus: the forum, a kind of city center where the most important civic buildings, temples and monuments would be located.

Athens (Greece)

Explanation:

Rome builds many cities, somewhat similar to one another. The ideas of the cities constructions taken from Greece. Athens played a significant role in showing Rome urban planning. Roman adopted the method of building structures in enormous size as the Athenians, along with temples, markets, and meeting places.  Athens being a center of culture and art, helped Rome in becoming a center of architecture, trade, culture, and art.

2018 means 2018 ce or common era

there have been other eras too including bce, which included way more years.