Delphi

Perched on the southern slopes of Mount Parnassus, Delphi was considered by the ancient Greeks to be the omphalos — the navel of the world. The site was sacred to Apollo, and the Oracle (Pythia) — a woman chosen from local families who would inhale vapours rising from a chasm in the earth while seated on a tripod — gave prophecies that were delivered to petitioners from across the Mediterranean world between approximately 800 BCE and 390 CE.

Modern geological surveys have identified two fault lines beneath the sanctuary that converge at the site of the adyton (inner sanctum). The intersection produces hallucinogenic gases including ethylene, which could account for the Pythia's altered states. Over 1,000 years of recorded responses survive, ranging from the cryptic ('a great kingdom will fall') to the surprisingly practical.