Mar'u'nopolis was an underground city on the planet Mars built by the Martians. When the nomadic Chitari invaded the red planet, the Martians took a stand to defend the last remaining cities before they would move on to Earth for more resources to exploit. Mar'u'nopolis became the last city that the Martians retreated. It is here that the metropolis houses the base of its orbital defense system that wiped out the majority of Chitari forces and forcing the remnants of the invaders to leave Mars. Tragically, the activation of defense system overloaded its generators that caused a large explosion that killed the remaining Martians in Mar'u'nopolis.