You are presented with a foremans office, with intricate design plans stuck on the wall detailing Tube systems, Restuarants, Burger Bars, Observatories, well the list is endless...and you don't actually understand some of the concepts being only a mere mortal.
You see a small nondescript door in the northern wall, with muddy footprints leading in though not out of it, it doesn't even seem to belong there! Apart from that the office is empty, and you begin to feel uneasy...