''In unexplored ruins of ancient civilizations disappeared reduced to a stage of myth and legend rests Zathias who is the only witness of their existence. The ruins date back several centuries and most of the facilities have been destroyed, they are partially functional. The walls are made of smooth rocks and crystals with patterns, water is dripping all over the place.''
This is just a document which is intended to inform readers, no one in this fictional universe is aware(or almost) of this location
Do you know People Jars, vat, pods, chambers in science fiction? This is the sort of thing that characters are asleep or some other genetic experience sometime. It's this but seen in a fantasy way