In The Expanse Mars, governed by Martian Congressional Republic, is a militaristic and technologically advanced society of over nine billion inhabitants. It is the major competitor of Earth & Luna, governed by United Nations. Earth, dragged down by overpopulation and climate change, envies Mars because of its society's high mobilization towards the shared goal of terraforming Mars. But in season 4 that shared goal and order of the Martian society is starting to erode as the new habitable planets beyond the rings are discovered (without the costly need of being terraformed as Mars does). As the interplanetary military tension is over veterans find themselves needless in the peace time society; crime and corruption is rising, and some even manage to sell older military tech to Belter pirate gangs.
Here is a collection with HD images from the Martian scenes in season 4 of The Expanse (open link in new tab to view in full resolution):
Exterior and interior of a shipyard for Martian fleet:
Martian school kids training for exam: