... is just outside Edinburgh: the Forth Rail Bridge. It was looking particularly fine a couple of days ago, i.e. any excuse to inflict another of my photos on the internet:
And it has an important connection to the sf/f world too, being the direct inspiration for The Bridge by Iain Banks, as can be seen from the cover of this edition. That was one of his earliest non-M books, and very good it is too: it was marketed as more or less mainstream fiction, but it's got more than a hint of industrial magic realism about it. A precursor of the New Weird, before anyone had even thought of the term.
As anyone paying attention will know, Mr. Banks, in his M incarnation, is big news at the moment, with the imminent release of the first Culture novel in years. Sometimes the hype for a new release runs way ahead of what's reasonable, but this is one of those occasions when the author's earned every single iota of the anticipation and more.
The Forth Rail Bridge also, coincidentally, lives up to the all the hype when you see it in the steel and brick flesh. Awesome.