Foundation facilities designated as Sites are covert facilities, meaning that while the existence of the facility is known to the public, such facilities are often disguised with government or corporate fronts. Sites are often built in relatively close proximity to civilian populations, where facilities would require such cover.
Foundation facilities designated as Areas are clandestine facilities, meaning that civilians are not aware of their existence at all. Such facilities are often built far away from civilian populations and may contain highly dangerous anomalies and extreme fail-safe measures such as on-site nuclear warheads.
Outposts are small facilities subordinate to a nearby Site or Area, used to contain immobile objects or to monitor anomalous locations.
Observation Posts are tiny facilities, often small standalone buildings or single units within larger buildings, and are typically used to monitor regional communications, nearby Foundation facilities, or immobile SCP objects. Many Observation Posts also serve as secure communications hubs or safe-houses for undercover Foundation agents.