The Buccaneers of Venus Collection (Three novels in one volume!) by Otis Adelbert Kline

since the day he had examined the abandoned airship.
        The beating of his heart was momentarily stilled by the sight which greeted his eyes when he turned on the light; directly in front of him stood what appeared to be a huge warrior, attired in armor from head to foot. Closer scrutiny, however, revealed the fact that he faced an empty suit of armor, for a mailed gauntlet clutching a heavy axe had fallen from one of the arms. It was this which had caused the clanging sound he had heard.
        The armor was skillfully wrought of a brownish metal which he at first took for bronze on account of its appearance. It was of a pattern unlike anything he had ever seen or heard of, and strikingly decorated with designs of inlaid gold set with brilliant jewels.
        Sharp metal spines projected from the top and back of the grotesque headpiece, while two large green jewels sparkled just above the movable visor like the eyes of some multi-horned reptile. In the visor itself, the true eyeholes were of a hard, thick crystal, and below them were small perforations to admit air. A huge broadsword hung from one side of the belt and a short club with a heavy spiked knob dangled from the other.
        On the floor before the figure lay a quantity of loose earth which had been carried with Grandon in his fall. He dashed the light upward and its rays revealed a ceiling nearly ten feet above his head, supported by timbers. He had broken through between two of the large timbers at a point where the cross-pieces were completely rotted away.
        Upon examining his surroundings he found that he was in a corridor about thirty feet in width, and extending in both directions as far as he could see. A double row of hexagonal columns supported the heavy ceiling beams, and before each column stood a figure similar to the one he had examined, with the exception that every alternate figure held a long, broad-bladed spear instead of an axe in the extended right gauntlet.
        The Earthman was in a quandary; he could not return via the opening through which he had fallen.
        From his fellow slaves he had heard legends of an ancient race of men called Albines, who were said to have at one time been masters of the sabits. These Albines wore suits of mail which effectually protected them from the creatures, and made slaves of whole colonies by raiding them and making prisoners of the queen and king sabits, for the soldiers and workers, being ever subject to the commands of their rulers, immediately became docile when the lives of their superiors were threatened. The Albines had vanished many years before—no one knew how or why—and the sabits had thenceforth turned the tables on man by enslaving the marsh-people.
        Grandon selected a suit of armor which appeared to be his size, and after a considerable struggle with the unfamiliar fastenings, succeeded in donning it. He had expected to feel stiff and awkward in his metal suit, and was therefore agreeably surprised when he found it both light and pliable; for though exceedingly hard and strong, the metal was as light as aluminium and so fashioned that the interlocking plates easily adjusted themselves to every movement of his body.
        Armed with sword, axe and club, he set out to explore the subterranean passageway, walking between the two rows of pillars that were guarded by the silent sentinels of a vanished race, and flashing his light in a semicircle before him.
        As he passed along, he noticed that the stone walls on both sides of him were carved at intervals with scenes and hieroglyphics. The scenes, for the most part, represented men attired in armor such as he wore, battling with sabits. He noticed, also, that in nearly every instance, the figures were pictured as striking the sabits between the eyes with spiked clubs although a few used axes; and one was represented as severing a soldier sabit's head from its body with a broadsword.
        One scene