Yanni visited a subterranean tunnel.

Renkon, the Imperial Martian Garden is in the Barsoom Colony." "Let's take the subterranean train to there, Neo!"

Not until after they had passed beyond the best work of the First Men in science and philosophy did the Second Men discover the remains of the great stone library in Siberia. A party of engineers happened upon it while they were preparing to sink a shaft for subterranean energy. The tablets were broken, disordered, weathered. Little by little, however, they were reconstructed and interpreted, with the aid of the pictorial dictionary. The finds were of extreme interest to the Second Men, but not in the manner which the Siberian party had intended, not as a store of scientific and philosophic truth, but as a vivid historical document. The view of the universe which the tablets recorded was both too naïve and too artificial; but the insight which they afforded into the mind of the earlier species was invaluable. So little of the old world had survived the volcanic epoch that the Second Men had failed hitherto to get a clear picture of their predecessors.