When the climb was accomplished and the discs were put away, Kirby found himself standing on the outer edge of a mediaeval paradise, of a magnificent plateau partly fortified by nature, partly by the hand of man. "Ah!" he cried in deep admiration, then followed Naida. The building--the castle--in the near distance, resembled a castle of Spain, save that there was greater beauty and subtlety of architecture. Turreted on all four corners, constructed of material which looked like blocks of natural glass, the fairylike structure was crowned by a gigantic tower of something which resembled obsidian. Up and up this tower soared until its gleaming black tip seemed almost to touch the glassy-radiant sky of the cavern. No people showed themselves, and Kirby saw that the bronze-studded portals set in the front of the castle were closed. Admiringly, he glanced at the surrounding land laid out in checkerboard patches of gardens and orchards where grew a bewildering variety of unknown fruits and blooms. Butterflies drifted past, and the air was freighted with the scent of flowers. Inside a walled enclosure, Kirby saw a good-sized plot heavily grown with the plant on which he had been subsisting. As they passed this ground, each of the girls, Naida leading, made a strange little bowing, gliding genuflection, and Kirby wondered. * * * * * Now, however, new sights distracted him as they crossed a port drawbridge above a deep moat which was a fairyland of aquatic plants. Although not a sound had come from the castle, the great entrance doors were swinging back. "Be ready," Naida whispered, "for almost anything. The doors are being opened by some of the palace guard. I have little doubt that word was long ago rushed to the caciques that we are come to them with an upper-world man!" Kirby answered with a nod. Then they passed the outer doors, passed inside, and Kirby blinked at what he saw. In a long hall decorated bewilderingly with a carven frieze in which appeared all of the symbols common to early Mexican religions, and many new ones, stood a row of bright suits of armor of the Sixteenth Century. From each suit peered the glassy face and shovel beard of a dead Conquistadore. So this was what happened to intruders from the upper world! The Conquistadore who kept his long watch beside the geyser was not the only one! Kirby felt an involuntary chill prickle up his back. But he was not given long to think before Naida, ignoring the gruesome array, clasped his arm. "Look! Behold!" And Kirby saw that with almost magical silence the whole wall at the end of the corridor was sliding back to reveal an enormous amphitheatre in the center of which stood a vast circular table. Ranged in a semicircle about that table, stood fifteen incredibly ancient men clad in long, glistening grey robes. Blanched beards trailed down the front of the garments until they all but touched the floor. The caciques!