Things Never Known
A few poles in the sand,
barely seen during high tide,
raw and random in the low.
Something was here.
Built in hope, with a promise,
a plan, now lost, No one left
to say just what.
All history, something missing,
an odd melancholy,
things never known
somehow still lost.
About this poem
There’s a word for it. A missing of things you have never known. But miss nonetheless. I can’t remember the word, so I wrote the poem.
Tom
Quarry House 
I found two words but I’m not sure either is quite what you are looking for: Hiraeth (Welsh) “a homesickness for somewhere you cannot return to, the nostalgia and the grief for the lost places of your past, places that never were.”
Saudade (Portugese) “A vague, constant desire for something that does not and probably cannot exist, a longing for someone of something loved and then lost.” from the book “Lost in Transltion”.
Maybe the Portugese is closest. But somewhere I have seen something even more precise. Thanks for taking the time to dig it up!