Rather than attempt a partial terraform like Venus, large craters and canals have atmospheres held within by a combination of gravity generators and positive pressure vents around the edges. Outside these habitats breathable air accumulates. The further away you get, the harder it is to breathe but that distance seems to grow larger every year.
The oldest and largest settlement in the Solar System is Mars City. It is also the first to complete construction of a UV filter dome covering its entire expanse. It is considered the seat of power in the Solar System for politics, socio-economics and – being the headquarters of the Red Dragon Syndicate – organized crime.
Cultural Aspect: Hong Kong
Other Aspects: The new cradle of humanity.
Phobos – With its remarkably close orbit, Phobos is gradually sinking into Mars (it will take about 50 million years). Though useless for colonization, Phobos’ proximity and reflectivity make it ideal for communication relies on its surface.
Deimos – Very low density for its size, a person could launch off Deimos by running since its escape velocity is only 7 mph. It is in a perfect position to anchor the primary Gate Station for Mars. In fact, when people say “Deimos”, they are more likely referring to the orbiting Deimos Gate Station.