Below is a list of the major features of the SGC broken down by level. Please keep in mind that these are general descriptions only, and that the SGC is very literally the size of a small city. Each level is several square kilometers.
Levels 1-10 are dedicated to the NORAD (North American Radar Defense) complex.
SGC administrative offices. This includes personnel, the quartermaster, and anything else that goes into the day-to-day paperwork that drives the SGC.
Security. The elevator from the surface stops at sublevel nine. In order to proceed further into the base, you must exit the elevator, check in with security and board a second elevator. Offices of the security force officers are located on sublevel nine.
Also, sublevel nine is designed with fortification in mind. The entire sublevel is arranged to provide any invader from outside the base a hardened target. The idea being, if they get through the main line of defense and into the base itself, sublevel nine provides a fire break where the defenders can hold the enemy indefinitely.
Since the beginning of the Stargate program, sublevel nine has been extensively overhauled, and now also supports several design features which will allow it to contain an invasion through the gate to the lower sublevels of the facility.
Accounting. Selected administrative offices for high security matters. Personnel quarters. Flight simulators.
Personnel Quarters. Most SGC Personnel are assigned on-base quarters in addition to any off-base living arrangements they might choose to make. This provides them with a place to stay in the event of a lockdown, or should they need to remain on base for an extended period of time.
Location of the quarters is based on a combination of seniority and responsibility. Majors and above, team CO's and 2IC are assigned private quarters on sublevel fifteen, while junior enlisted personnel are crowded together in large barracks on sublevels ten and eleven, assigned only a bunk and a locker.
SG team members are always assigned either private or semi-private rooms. In cases where they are assigned semi-private rooms, they are generally given great freedom in selecting their roommmate.
Cultural sciences labs and library. All anthropologists, archeologists, historians and sociologists are assigned an office on these levels (unless they also have credentials in one of the hard sciences, or are a team CO). In addition to the offices, there are several labs devoted to artifact preservation, and a massive library with one of the finest collections of anthropological and historical texts in the world.
Science labs. Most science specialists are assigned private labs, though seniority tends to determine just how large a lab they get. There are also several large shared labratories.
Comissary. Rec-rooms. Gym.
Infirmary/surgery. Medical isolation rooms.
Command level. General Hammond's office, CO's row (offices for team commanders), main briefing room. Command post for the Gate Room Security Detachment (GRSD).
Gate control room. Routine weapons firing range and [limited] armory.
Gate room. GRSD ready room. Armory.
VIP Quarters. MALP storage.
Isolation and confinement.
Main power generators.
Experimental weapons research and storage.
Experimental weapons firing range.
We'd like to thank Brian B. for his help in the compilation of these Stargate guides.