National Geographic ranks ATM as its number 1 sacred cave of the world. Cayo's Joe Awe talks about it in this article.
"The National Geographic’s recent article was extracted from their book, Sacred Places of a Lifetime, and lists their top cave destinations from around the world, including caverns in India, Sri Lanka, Greece, China, Malta, France, Ethiopia and Italy, as well as Belize. Mr Awe said he believes that researchers have just barely scratched the surface, so to speak, of Belize’s sacred Maya caves, which exist within a vast network of naturally formed caves, underground rivers and cenotes, or deep sinkholes. The ancient Maya considered caves and cenotes to be portals to a cosmological underworld and revered them as places where their priests and rulers could communicate with and send offerings to appease their deities and to petition them for divine assistance. Actun Tunichil Muknal, for instance, features impressive altars and ceremonial areas and is packed with pottery and shards as well as numerous implements and artefacts made of jade, obsidian, bone and other materials. It’s most well-known feature is the famous 'Crystal Maiden', the intact skeleton of a young sacrificial woman that, due to an accumulation of calcium carbonate over the years, sparkles eerily in torchlight."