Vast networks of halls, subterranean artificial rooms and natural caves revised sometimes by the hand of the man to act as organized shelter and as communications in Antique and ancient underground cities.

Japan	Scotland	Turkey	Peru
USA	France	Greece	Cyprus
Corsica	Crete	Malta	Pacific Islands
Sardinia	Sicily	Tahiti	India
Iran	Italy	Ecuador	Lebanon
Mexico	Palestine	Spain	Russia
Egypt	Tasmania	Tibet	Chine
Vietnam	Malaysia