User blog comment:ChishioKunrin/The Schnee Dust Company's treatment of Faunus workers/@comment-25368963-20150118051529/@comment-3146930-20150118143436

The timeline of Mountain Glenn's downfall has always annoyed me. From the look of it, the tunnel into the city was made as a quick means in and out of Vale for anyone living or working in MG. However the surface was eventually overrun by Grimm so people escaped to the underground cave network. However instead of using the tunnels to escape back to Vale, they instead started building the city underground. However when they tried to expand, they blasted open a wall and the city was flooded with underground Grimm. As a result the subway tunnel was closed off to prevent the Grimm from entering and presumably everyone left in the underground city died horribly.