Delta Labs

Delta Labs, otherwise known as the Delta Complex, is one of the prominent locales in Doom 3. It's also one of the hardest parts of the game as the player fights more than a hundred demons, suffers from hallucinations, and must unlock several lockers. The lack of cutscenes makes gameplay constant, though Dr. Betruger constantly addresses the player and the demons over the loudspeakers. In addition, the main portal is located in the Delta Labs.

It consist of 4 sectors separated in different compartments and connected with a series of elevators. It is quite infested but still has a few operational devices, albeit in an emergency power mode.

The player returns to Delta Labs after retrieving the Soul Cube to find the area in ruins and coated with demonic growth.

Delta Labs also makes an appearance in Resurrection of Evil, though only barely recognizable.

Sector 1
Sector 1 is the main area and entrance to the Delta Complex. It houses Power, Control, Administration, Storage Area, and its own Reactor. The only entrances are the Monorail Station and the CPU Complex. Sector 1 also has the main warehouse in the Delta Complex.

Sector 2
Sector 2 is divided into two areas. 2A is the main Medical Facility in the UAC. 2A also has one of the first teleporters in the UAC. 2B houses a "demons exhibition area," specimen (from Hell) handling area, and research facility. 2B also does research on Site 3's main artifact, the Soul Cube.

Sector 3
Sector 3 has test teleportation. The teleport chambers are divided into 3 chambers. The first chamber has two locations: the room itself, and the upstairs of the chamber. The second chamber has three locations: the room itself, a Hallway, and a Storage Room. And the last chamber (which is the main teleporter in this sector) has four locations: another Storage Room, a Hallway near Test Chamber 1, an office near Test Chamber 3, and near the entrance to Sector 4. It also has a series of quarantine centers, intended to observe the effect of teleportation on humans (and to house "failed experiments"). There's also a specific storage area to store organs and tissue for shipment. A BFG is stored in this sector.

Sector 4
Sector 4 is the smallest sector, but houses the Main Portal to Hell. As this is the site where the invasion began, much of this area suffered severe damage, as the hallways are littered with human skeletons and remains, and drenched with blood.

Levels that take place in the Delta Labs

 * Delta Labs - Level 1: Union Aerospace Research Division
 * Delta Labs - Level 2a: Union Aerospace Research Division
 * Delta Labs - Level 2b: Union Aerospace Research Division
 * Delta Labs - Level 3: Union Aerospace Research Division
 * Delta Labs - Level 4: Union Aerospace Research Division
 * Delta Complex: Union Aerospace Research Division
 * Delta Labs - Unknown: Union Aerospace Research Division

Trivia

 * The Delta Complex is placed near Site 3, connected with a rail system.
 * Delta Labs makes another appearance in Doom 3: Resurrection of Evil, and some areas of Delta Labs are recognizable from the original Doom 3.
 * In Delta Labs Sector 1, one of the terminal states that a party would be thrown in Sector 4. This can explain the famous party hat Chainsaw Zombie found in Delta Labs Sector 4.