High in the mountains of South America stand traces of ancient civilizations with similarities to the ancient Egyptian civilization. Structures built with large blocks of stone closely trimmed and fitted in much the same manner as the Great Pyramids. Space ports on high mountain plateaus, which can be seen clearly from space but scarcely discerned while on the ground. In the steamy jungles further north lie the outlines of cities, abandoned for no known reason. The land is fertile, the water supply ample, yet they lie unattended and uninhabited. Legend has it that human sacrifices were performed atop pyramid like platforms, hearts ripped from the chests of the living, yet no trace of these practices exist among the local peoples. Who built these, and where did they go?
All these traces of an ancient civilization are just more remnants left by the 3rd Density hominoid visitors from the 12th Planet, who left the Earth because they were put into quarantine by the Council of Worlds due to the havoc they were causing on Earth. Human sacrifices, never an indigenous practice, were also abandoned, as this grim method of punishment was only used by the dominant visitors to keep their restive human slaves in line. After their exit the startled humans left behind wandered off or toyed with playing politics by becoming, for a day, the new rulers. Where one does not have the technology to make a city function, the paved streets and stone structures become a burden. So much farther to walk to the fields to be tilled or the game to be killed. Why walk all those weary steps? Soon the cities were deserted by all but monkeys, lizards, and the vines that creep over everything in the jungles.