[kolinko]

Perhaps if you're building a cellar. If you want to make a 10-story building - even in a virgin terrain, it's a complicated operation.

Not to mention that you need to make the materials such that they resist a huge side pressure, water leaks and so on.

Psychological costs are also costs.

[Retric]

Water leaks are not going to be a problem on mars. Significantly lower gravity 3.711 m/s vs 9.8m/s also drastically lowers pressure from burrowing.

[clock_tower]

Wide-open spaces, even enclosed ones, can reduce the psychological burden of confinement quite a bit -- there's a variety of Russian strategic-missile submarine with a swimming pool, for example. This subject also comes up frequently in SF (science fiction, not San Francisco, which has the opposite problem); there was some discussion of it on the "Atomic Rocket" worldbuilding guide, IIRC.

[lambdadmitry]

I… I think the picture of that "pool" in your head is slightly wrong [1].

Tangential: the source [2] is pretty interesting.

[1]: http://pics.livejournal.com/igor113/pic/001e551p

[2]: http://igor113.livejournal.com/27205.html

[ChefDenominator]

Why build layers at all? Urban concentrations too high?