On the top, and there it was - massive and unguarded, the ventilation shaft for the tunnel. The 33 meter depth of the shaft can be judged from the earlier pictures that show the hill side above the embankment leading to the tunnel. Apart from the you folks on the IRFCA, I can confidently say that not even 5 people in Pune know about this shaft - and skyline of our teeming metropolis with 4.5 million souls can seen just over there....