When I was young I had a book about the age of steam. One memorable piece in the book was about the Titanic; the other was about the Britannia Bridge, Robert Stephenson's 1826 marvel across the Menai Strait that was so unforgivably destroyed by fire in 1970.
The magnificent stone lions were the main reason for me cycling all the way from Chester to see the bridge, but I also wanted to see the one remaining section of the iron tubes.
Most photographs give little idea of the scale of Stephenson's construction, although a train would of course mostly fill the internal space. Also obvious to a much closer look is how the heat of the great fire buckled the thick iron plates, so that the tubes would have had almost nothing at right-angles afterwards.