I too like the use of the word 'portal' in describing this photograph...it does seem like an entrance to another world and I bet, especially.... during a dark and stormy night.
I really like the angle of your photo of this bridge and to me the design seems out of the ordinary. Quite a beautiful design .
My wife and I just came back from a trip to Alberta and came across a heritage site of an old (for Canada), no longer in use aqueduct that had been built at the turn of the last century by the Canadian Pacific Railway.
The architectural structure was exceptional, strikingly symmetrical ...the lines, to me, reminiscent of the much older Roman Aqueducts. In any event, historical or otherwise
, I spent some time photographing various angles.