Shan ara chronicles has just that and I searched it in tvtropes: https://tvtropes.org/pmwiki/pmwiki.php/Series/TheShannaraChronicles#:~:text=The%20Shannara%20Chronicles%20is%20an%20American%20post-apocalyptic%20fantasy%20drama%20television
The Reveal: Not that the characters particularly care, but Safehold turns out to be the 3000 year old remains of San Francisco
Shan ara chronicles has just that and I searched it in tvtropes: https://tvtropes.org/pmwiki/pmwiki.php/Series/TheShannaraChronicles#:~:text=The%20Shannara%20Chronicles%20is%20an%20American%20post-apocalyptic%20fantasy%20drama%20television
The Reveal: Not that the characters particularly care, but Safehold turns out to be the 3000 year old remains of San Francisco