In a stunning setting in the shade of a bamboo grove, a 1km-long cement track leads to the Konyu railway cutting. Prisoners were force to work here uninterrupted night and day to dig a passage through the huge mass of rocks. The sight of fires lit at night seemed to the exhausted workers to be the flames to the gates of Hell, hence the name of the pass. A colossal block of stone, cut in two, bears witness to the almost intolerable work of prisoners who had only the most basic of tools at their disposal.