Mars

Mars is the fourth planet from the Sun in the Solar System. It was terraformed in the 21st century and became the most populated planet. Mars was sometimes nicknamed as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface.
Mars colonies is mostly built inside large craters on the surface, covered by artificial atmosphere that was constantly replenished via large devices at the edge. In this way, a colony could be established with atmospheric and climatic features similar to those of Earth. Large cables connected different crater-cities and covered highways allowed travel between. Tharsis City and Alba City were two cities on Mars.
There were at least two universities on Mars: Mars University and SIT.
Mars has a police force, the Mars Police Department, and a military organization, the Mars Army.