You will need to produce food, mandatory to sustain your population, wine, oil, pottery, weapons, furniture, and other items you can trade. At the same time, you must pay attention to the production and distribution lines so that people and resources can move adequately (just like the trade routes of The Settlers).
You have to build and expand a city, deciding the residential zones (in Caesar II, the houses are built, in Caesar III, you choose the areas, as you do in SimCity) but also infrastructures, security, and religious buildings, recreational areas and so on.
Caesar combines both elements of Sim City 2000 and The Settlers II. The game is set during classical antiquity, and all aspects of typical Roman city life are reproduced faithfully: food, resources, religion, military, and so on. It's the third chapter of the popular series Caesar, created by David Lester. Caesar III is a city-building historical sim created by Impression Games and published by Sierra in 1998.