Site 2 is a dig-site in the UAC. It is the smallest dig-site and has the smallest Caverns in the UAC. The Caverns aren't really seen here, only the Warehouse. But in Pierce Rogers' video, it shows some temples seen in Site 2. The only entrance/exit known is: the Monorail Station.
Research at Site 2 was declared sufficiently complete by the EAP council under direction of Charles Hollies as of September 5, 2145, and was scheduled to have environmental processors shut down on October 1 in order to conserve power. Worker Yon Brady reported that all artifacts and security team supplies were moved out and the caverns sealed as of October 11. However, artifact transfer to Site 3 continued as late as October 27, when Delta researcher Phil Wilson complained about improperly marked artifacts still arriving.
Some Site 2 resources were brought back online as of October 15 due to need for additional processing space and power, as ongoing processing of telemetry from the Delta Labs teleporter research projects was consuming all available resources at the CPU complex. However, the day before this, a hack was detected coming from Site 2 office S2-038 by Mars Security IT Division tech Tony Bates, who logged the incident in his PDA due to not understanding how a hack could originate from a sector of the base with no power. It is possible that this hack was one of the attempts by Dr. Richard Meyers to obtain Malcolm Betruger's private files.
The Site 2 caverns and facilities are never seen in Doom 3 or in any of its expansions, beyond the monorail station and its attached warehouse area, which were the only areas kept fully operational as a route to Site 3 and Delta. The only sights that can be seen of it are those offered by the ancient civilization video disk.