Location from acotar-silver-flames by
An ancient subterranean labyrinth carved into the heart of a mountain on the Night Court's border, holding beings so old and dangerous that even the High Lords fear to speak their names.
The Prison is not a place of justice but of containment—a vault for horrors the courts could not kill and dared not leave free. Its corridors spiral downward into the mountain's roots, each level sealed with wards older than the Treaty, and at its deepest depths lie cells that hold things that predate the High Fae themselves. No one enters willingly, and no one who enters uninvited has ever returned to tell of what they found.
A black, windowless mountain rises from a barren plain, its slopes scarred by no path and its peak crowned with a single iron door that has not opened in living memory. Inside, the air is cold and still, thick with the weight of millennia, and the stone walls weep a dark, oily moisture that smells of salt and rot. The only light comes from faefire globes that gutter and dim as if the darkness itself is hungry.
Also known as: The Mountain of the Prison, The Iron Door, The Deep Vault, The Old Prison