The top door beam of Entry hall 480 was a single, huge block of hard black rock dark rock, nine arm-lengths wide, three arm-lengths high, and four arm-lengths deep, weighing more than sixty-four tons. It had been quarried from the roots of the ancient land-wide craton, dressed with diamond-tipped irons, and hoisted onto two fluted jambs of dark green snake-like with such tiny care that not even a strand of horsehair could be forced between the joints.
Carved across the entire face of the top door beam was a massive sky-high frieze. It depicted the heavens not as an open sky of clouds and sunlight. But as a vast, inverted ocean of liquid darkness, through which seventy-two star-patterns swam like glowing deep-sea creatures. At the center of the frieze. There, the keystone bore the upright load of the overlying mountain, was an intaglio carving of an inverted bell surrounded by eight streaming rays.
Qiao Ming stopped three paces before the top door beam, his bare feet planted flat upon the threshold stone. He raised his lantern, letting the focused amber light up the central glyph. The carving was sharp as the day it was cut cleanly, free of the salt encrustation that scarred the outer rows of stone pillars. In the cold, dry air of the lower vault, the stone smelled faintly of crushed sulfur and dried river-clay.
