Documenting the world's strategic underground facilities, deep-engineering tunnel projects, and military installations through a rigorous, evidence-graded framework.
Strategic hardened sites, command centers, and government continuity facilities worldwide.
Large-scale subterranean transit, utility, and research tunnel engineering projects worldwide.
Surface installations with documented or corroborated subterranean components — US first.
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Verified by official government documentation or declassified records.
Supported by multiple credible independent sources, lacks official confirmation.
Single credible source, not yet corroborated.
Contradicted by credible counter-evidence.
Demonstrably false — evidence actively contradicts the claim.