I was reading a 1950's book on the redevelopment of Coventry after the blitz, and read "after extensive bombing much of the old city was demolished and rebuilt. A central ringroad was constructed and the river Sherbourne culvated..."
So, asked around and found out where the river comes out, and myself and Raddog waded through the river and into the mouth of the culvet. Much bigger and longer than I ever expected. We went underground by Gulson Road, came out right in the heart of the city by Cross Cheaping, and then back under all the way to the skydome! For those that are not farmiliar with cov that is at least a half a hour walk top side!
Much to see down the tunnels. Bridges from before the culvet are still in place, they have just been concreted around. Lots of cool stalagtites, pipes and waterfalls. Other smaller tunnels run off the main one which are almost as long again!