Tsagaan Agui

Tsagaan Agui (Mongolian), located in the Gobi Desert of southwest-central Mongolia, is a stratified Paleolithic cave site with a calcium carbonate crystal-lined inner chamber. The cave has yielded abundant archaeological materials, some perhaps as old as ca. 700,000 years ago. The cave has been (and continues to be) used sporadically by Buddhists as a pilgrimage destination. The cave has been under the protection of the Mongolian government since 1988.

Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).