how critical is passive stability?

> In fact, there's perhaps an interesting challenge for the group: can
> you find any town or village of at least 5000 people, which is
> constrained by geography into a narrow strip on the order of 250 m
> wide?

There are probably some towns in valleys in Bhutan that fit that
criterion. Paro has a population of 4500, but I can't tell how wide it
is, because Google Earth doesn't have good resolution in Bhutan, and I
can't find any online street maps.

Also, last night I flipped through a book that reminded me of the cliff
dwellings at Mesa Verde, Colorado. It seems that the largest of those
(Cliff Palace or Long House) are smaller in area than you want, but
they have high aspect ratios and had peak populations near 1000:
http://www.nps.gov/meve/cliff_dwellings/cliff_dwellings_home.htm

-Phil