Kennet and Avon Canal
You get two aqueducts for the price of one in this entry.
The historical part of me says I should display the old river aqueduct first, but instead I will show you the new one recently built to span the A350 between Semington and Melksham.
Yes, its in concrete but can you imagine anyone paying the sort of money this one cost in the 1960's, when the Kennet and Avon laid abandoned with little hope of getting the nearby Caen Hill flight restored.
And then there is the old Semington Aqueduct, which has been quietly going about its business, carrying the Kennet and Avon over Semington Brook, for over 200 years. It was completed in 1807, is a mere 46 feet long and has a Grade 2 listed attached to it.