what are the obstacles preventing a city from being built underground?

Edited January 31, 201114 yr by dragonstar57

ventilation would be my first thought.

 

second thought is drainage if it's below sea level.

Edited January 31, 201114 yr by lemur

Money.

 

second thought is drainage if it's below sea level.

Drainage would be a problem if it was below the water table (which could be well above sea level).

Earthquake is one of the factors.

Motivation.

The Seattle Underground is on my list of to-dos.

Great, you just proposed making this

http://en.wikipedia.org/wiki/Seasonal_affective_disorder

into a practically fatal illness.

Even the rest of us would get tired of the lack of light.

NO atmosphere below the surface that will make them spend a lot of money for proper ventilation!

And also you can't grow fully when you have no sunlight!

NO atmosphere below the surface that will make them spend a lot of money for proper ventilation!

And also you can't grow fully when you have no sunlight!

UV lamps?

plants for the ventilation?

I would suggest that an underground city is only useful if the volume of living space is a bottleneck at a certain location (I'm thinking of Manhattan for example where population density is really high).

 

For most places on earth however, the bottleneck is not volume, but it's surface area (or sunlight, which scales with surface area).

Only under the assumption that you have unlimited energy (future scenarios with nuclear fusion, or really clean fission) can volume become the limiting factor on earth.