Which major soviet cities represented the farthest advance of the german army into the soviet union?

Stalingrad is the major Soviet city that represented the farthest advancement of the Germany army during World War II.

The Battle of Stalingrad, that took place from July 1942- February 1943, was a successful Soviet defense of the city against the German advances. This was considered a significant turning point in the war, as it marked the furthest advancement of the German army. This is also remembered as one of the bloodiest battles, as there were nearly 2 million casualties.