Sector 0 is a location in Midgar in Final Fantasy VII. Above ground, it is the space on which Shinra Headquarters stands. Below, it is the main base for Deepground in Dirge of Cerberus -Final Fantasy VII-. The area seems to be a war-torn city with burned ruins of buildings. Though it is entirely underground, there is enough space above for helicopters to fly. Above, there is no sky, only an empty blackness that looks similar to night. The Sector 0 Reactor is located here.
Sector 0 is visited early on by Cloud, Barret, and Tifa in order to gain access to the Shinra Headquarters to rescue Aeris. Later on, it is visited again in order to prevent the firing of the Sister Ray.