Opened a wide plaza paved with the volcanic glass, but black as that down which we had sped from the chamber of the Moon Pool.

It shone like a mirrored lakelet of jet; on each side of it arose what at first glance seemed towering bulwarks of the same ebon obsidian; at second, revealed themselves as structures hewn and set in place by men; polished faces pierced by dozens of high, narrow windows.
Down each facade a stairway fell, broken by small landings on which a door opened; they dropped to a broad ledge of greyish stone edging the lip of this midnight pool and upon it also fell two wide flights from either side of the bridge platform.

Along all four stairways the guards were ranged; and here and there against the ledge stood the shells--in a curiously comforting resemblance to parked motors in our own world.
The sombre walls bulked high; curved and ended in two obelisked pillars from which, like a tremendous curtain, stretched a barrier of that tenebrous gloom which, though weightless as shadow itself, I now knew to be as impenetrable as the veil between life and death.

In this murk, unlike all others I had seen, I sensed movement, a quivering, a tremor constant and rhythmic; not to be seen, yet caught by some subtle sense; as though through it beat a swift pulse of--black light.
The green dwarf turned the _corial_ slowly to the edge at the right; crept cautiously on toward where, not more than a hundred feet from the barrier, a low, wide entrance opened in the fort.

Guarding its threshold stood two guards, armed with broadswords, double-handed, terminating in a wide lunette mouthed with murderous fangs.