Dungeon Entrance at the Edge of the World

Publisher's blurb:

There is a cliff that lies at the top of a mountain—a cliff so steep, that some say it is the edge of the world. Indeed, it seems that way to many, for it is a strange and mysterious place. No one remembers who made it, or why—but holes have been eaten into the ground, lined with rocky cervices, each leading into dark and deadly caves, uncharted by man. But the main cave—the tomb, to which this ancient entrance beckons—well… Few have entered, and made it out alive.