The battle cost 800 thousands of lifes from German side (including Hungarian, Croatian, Italian and Romanian soldiers) and 1.1 million of Soviet soldiers and civilians.
Almost all civilians (450.000) stayed in the city (it was difficult to organize evacuation because of river on the east part of city) and almost all of them died.
10th NKVD division was the first who met Nazi military machine. In the beginning of the battle this division consisted from 7568 soldiers. After few weeks of fierce fighting only 200 people left... But their heroic death gave a chance to bring reserves to the city.
During the Battle of Stalingrad soldiers were fighting for every meter! Military operations were planned to seize houses and sometimes apartments. During TYPICAL fighting for a single apartment during 5 hours both side lost up to 1 thousand soldiers.
Sometimes there was basement under control of Nazi, first and second floor were under control of Soviet troops and upper floors were under control of German soldiers. The control of particular floor or apartment during the fight passed from hand to hand many times. The level of violence during melee fights was unbelievable. Many soldiers loose mind.
Legendary Pavlov's House was marked at German military maps like 'The Fortress':
There were so many corpses on the streets that soldiers use it to create barricades.
From the memories of German soldiers: "You have to thank God for each hour that you remain alive here". "…Here is the hell. Less then 30 people left from my company [military unit ~200 soldiers]. Stalingrad is the grave for German soldiers''.
From unsent letter killed at Stalingrad German officer:
"We have just one kilometer left to the river Volga, but we just can not get through... We are fighting for one kilometer longer than for whole France, but Russians are like blocks of stone!"
The elevator near the Volga river was one of the centers of fighting in Stalingrad:
Average life duration of a soldier in Stalingrad was 24 hours...
But veterans of the Battle of Stalingrad (after 74 years) still have nightmares...
P.S. Photos are from http://www.softmixer.com/