Port Renatus is the capital city of Mars (Sol IV), and is the first permanent Human settlement to be built on a planet outside Earth (Sol III). Once Mars' second attempted terraformation was successfully completed in the 22nd century SEY, Port Renatus grew into a city-sized settlement as it became the de facto spaceport for all persons arriving to further develop the planet.
The architecture of Port Renatus is studied by historians as an example of Humanity's first attempts to build modular cities.