I took this photo as we started the 3/5 mile walk through the tunnel. The towpath and much of the wooden railing is all original. In fact, you can still see rope burns in the wood railings from the mules pulling the boats through. It got pretty dark in there so we kept a flashlight on the whole way. 2 bikers rode by us with their headlights beaming.
I couldn't help but think of Justice William O. Douglas and his famous walk of the entire canal in 1954. That walk, with Washington Post editors, saved this canal from being paved over into a highway.