In general, nocturnal of subterranean species have less interest in the visual world, and depend on other sensory modalities. Visual capacity is a continuum, with humans falling somewhere in the center.
There are gateways to the surface everywhere.
The traffic moves both ways. Things come up: things go down. One of those gateways is the Holland Tunnel with the implication that Dante had literally been describing Hell, having seen its subsurface chambers.
Soon the Army Corps of Engineers gets involved. "They were tasked to reinforce tunnels, devise new transport systems, drill shafts, build elevators, bore channels, and erect whole camps underground. They even paved parking lots three thousand feet beneath the surface. Road…Read more >