THE CUSTOMS HOUSE.
Between London Bridge and the Tower, and having, separating it from the Thames, a broad quay that was for long almost the only riverside walk in London open to the public, is the Customs House. Five earlier buildings on the same site were destroyed by fire, and the present structure was erected in 1814-17, the fine fašade being designed by Sir R. Smirke. Some 2,000 officials are employed at the Customs House, and in its famous Long Room alone -190 ft. by 66 ft. - eighty clerks are habitually engaged. This is not surprising, for the trade of the Port of London is by far the greatest of any port in the world. The building, which is entered from Lower Thames Street, contains an interesting Smuggling Museum.
source: The Queen's London : a Pictorial and Descriptive Record of the Streets, Buildings, Parks and Scenery of the Great Metropolis, 1896