W.Y. Evans-Wentz - Chalchatongo and Mictlan, the Aztec land of the dead
Type of Spiritual Experience
A description of the experience
The Fairy-Faith in Celtic Countries, by W.Y. Evans-Wentz, 
The worship of Mithras, the Persian god of created light and all earthly wisdom, who in time became identified with the sun, was conducted in natural and artificial caves found in every part of the Roman Empire where his cult flourished until superseded by Christianity; and in these caves very elaborate initiations of seven degrees were carried out.
The cave itself signified the lower world, into which during the ordeals of initiation the neophyte was supposed to enter while out of the physical body, that the soul might be purged by many trials.
In Mexico the cavern of Chalchatongo led to the plains of paradise, evidently through initiations; and Mictlan, a subterranean temple, similarly led to the Aztec land of the dead.