Domes? More practically: We already know that martian soil can be made into bricks. So we could build thick masonry arch tunnels in trenches, then cover them ov

Domes? More practically: We already know that martian soil can be made into bricks. So we could build thick masonry arch tunnels in trenches, then cover them over with soil. This would provide radiation shielding, and the weight could then counteract internal pressurization. Such tunnels could be made airtight by using impermeable plastics, or by using frozen water, which would be literally rock hard at martian temperatures.