If only the hollow earth theory were true...
@129828 It was already blown up...
Despite all that science, its probably because some retard put Plasma in every single one of the buildings.
Because, in the ground there is a higher tempature then on the surface. Judging how this is an Underground City, we'll need to think about it generating it's own heat, or.. being close to the planet's core. This makes the metal they'd find for building already brittle and, well, hot... YOU KNOW WHAT, I'M DONE WITH THIS.
Why does the city just melt?