Last Sunday, I attended a very rare tour of an amazing place in London: the Thames Tunnel, the first such structure to be constructed — in the early 19th century — under a navigable river. (More about the tunnel at Wikipedia.) Though the tunnel was originally used by pedestrians, it’s now part of the Overground network and isn’t usually open to tourists. So this was a special event. (BBC News has some coverage of the tours.)
Unfortunately, not much of the original tunnel remains, but how often do you get a chance to walk on the trackbed?
I’m sharing some photos from the tour this week. Above, entering the tunnel, from Rotherhithe station south of the Thames.