no prob! didnt have my bookmarks handy on my work computer the other day, but check out the second image on the link below, the yellow section on the map is the only part of the tunnel still open today.
really makes me wish i got to see it with all the different tunnels and rooms still open.
side note: about halfway down the tunnel (VERY dark, bring a 1000> lumen flashlight with you) theres the remains of a station. you can tell its the station because the supports for the ceiling are more decorated and round. its a cool sight!