Reading Viaduct {Philadelphia,Pa}

I found about this project while doing research on another bridge I was looking for some info about,after reading alot about it I saw there was a tour that weekend and after walking around Center City for about 5 miles.I just sat there and thought about it for a minute on how this looked back in the early 1920's and how they built it.
   The tunnel was the a nice treat after the tour was over I saw the guide was walking down the street and he thank me for taking the the tour and I said I really would have liked to see the underground tunnel.He then to my surprise well said let's go and away we went and to see what they did back the early 1900's is truely amazing it is something that must see in person.