Contemporary article on the Moscow obstacles...

obstacles the Germans faced on the Eastern Front when it came to taking Moscow. They are pretty well explained in this old four page article from Time magazine from Dec. 8th of 1941. Down near the bottom of the first page, is this:

It is huge: it covers 117 square miles. It is a maze of irregularly traced, winding streets. It is remarkably self-sufficient. Its industry, 14% of all Russia's, is doing all it can for defense. Its water supply is so far safe: the great Uchinsk Reservoir, 16 miles north of the city, the older Mytischi mineral springs system, ten miles northeast, and the Rublievo river-water system, ten miles west, are all still out of the enemy's reach. Its sources of electrical power lie farther afield, but they are well scattered and, so far, only slightly hampered.

See:

World War: Death on the Approaches - TIME

It is the "cover story" from that issue, with Fedor von Bock on the cover.