Quizzy "9"

  Thanks folks, shall we continue on this theme for a while? 

        Underground again and during world war 2 this was probably the world's biggest undergound factory, where are we and what was the the original purpose of this place. 

  Sorry guys still off track.

                I have worked in the past in one part of the underground complex but then it was used as MOD storage- and me being the smallest got the job of measuring the ventilation  shafts and ducts, the impellars may have been about 20 foot diameter but the ducts narrowed to no more than a couple of bricks wide at the ends and was there some dust , dirt, and old rubish in them- think I must have been the first down the ends at that time for around 30 or 40 years. Oh I drift off on a memory ramble, John, you could say your first answer was close but at the same time way off.