The Natural Philosopher wrote:
The more I look at the average urban and suburban sprawl the more I feel
that actually what we should be doing is putting the roads deep down,
the houses just under the surface with light pipes and the gardens and
parks on top...Hobbiton? possibly :-)

What do you think are the pros and cons of this from a cost/benefit
environmental and general living feeling?

Cons
====

o Damp/drainage.
o Radon, and other heavier than air poisonous and toxic gases.
o Sewerage and waste water disposal becomes more difficult. Either
considerably deeper, and therefore more expensive, or widespread use of
S*n*f*o*s. Oh joy.
o Careful insulation required, otherwise heating bills will skyrocket
as you try to heat up the surrounding earth.

Cheers,

Sid