The Hollows

A massive planet wide series of metal lined under ground tunnels. The tunnels connect at many evenly spaced points branching off to many other tunnels at said points like the vertex of a many sided polygon. The geometric shape has lead some scholars to believe that the Hollows were once used as a structural framework that the planet was constructed around, this theory of a constructed planet is the subject of many debates.

Type

Megastructure, Planetary scale