THE EAST END OF LONDON was not a common destination for the upper- or middle-class sightseer in the early nineteenth century. The requisite steamer ride down the Thames from London Bridge for the excursion out of the city to Greenwich would show, along the way, in the words of one tourist, “The Custom House and the Tower, the only prominent objects rising out of the dreary range of shabbiness which stretches along close to the water's edge” (Hawthorne 232–33). There was one exception to the habit of overlooking the East End: a significant proportion of the twenty-four million persons who passed through the Thames Tunnel between Wapping and Rotherhithe from 1827 to 1865 had indeed made the eastward excursion expressly for that purpose. Essential viewing at the time but little studied since, the history of the Thames Tunnel indicates the stakes and the consequences of remapping the urban topography of London during the era when middle-class tourism was being invented. Comprised of two 1200-foot-long arched passageways joined by a wall of open arches in an overall brickworked space of 22 1/2 feet high by 38 feet wide (Bobrick 58), the Tunnel was unique among the obligatory sights of the city in that it was also a practical thoroughfare employed as such almost wholly by the working classes. It was open twenty-four hours a day, and, as one visitor noted, it offered the unusual experience of emerging “in the midst of one of the most unintelligible, forlorn, and forsaken districts of London or the world” (Catlin 2: 112–13; qtd. in Altick 373), the docklands and slums of the East End. Through a half-century as a symbolic hub of London life from the years of its design and excavation (1824–43) to its conversion to a railway tunnel on the East London Line in 1869, the Thames Tunnel mobilized the tensions in the modernizing city between technological progress and social repression into a dense network of underground myths.