I’m looking forward to hearing Elon Musk’s plans for of his Mars colonization project, to be announced at the International Astronautical Congress in Guadalajara, Mexico. Building for a human settlement on Mars is something into which I have put a lot of thought over the years.
Most of a real Martian city must be built underground using the soil for radiation protection. Mars has almost no magnetic field and a very thin atmosphere so the surface receives hard radiation at much higher levels than on Earth.
One must think of a Martian City as a large underground space station.
There are three main approaches to architectural design on Mars. One is to build inside of caves or possible lava tubes. Second is to build on the surface then cover the structures with soil. Third is to build in the rim of an impact crater.
An impact crater is produced by a meteor crashing at high speed on to a planet of moon. The impact troughs out large amounts of dirt and rocks forming a crater floor and round rim of debris. Over millions of years the rim settles becoming almost as dense as rock.
There are usually fissures and cracks in the rim wall allowing for entry into cave like environments. Ideal for immediate radiation protection for a start-up base camp.
In my opinion option three is the best for a Mars City because the rim can be hollowed out in two directions at the same time creating a circular city master plan and efficient internal circulation systems.
The rim also allows easy surface access to inside and outside of the crater. Furthermore the rim provides additional side radiation protection for people working inside the crater.
Like a submarine the City must be divided into many airtight sections. If there is a fire or a breach to the Martian atmosphere a section can be evacuated and sealed from the rest of the City. Emergency crews in Mars suits and robots can enter through airlocks to fix the problem.