higher and higher they went , until they were in the clearing , over them was the radiant night sky littered with streaks of green aurora lights and innumerous twinkling blue stars , underneath them was the shroud of dense fog that covered the whole of the underworld and presently hid it completely from their eyes , and a little in front of them , was an ominous looking gothic clock tower , its ginormous height making it the only structure in the visible range which jutted above all that fog .