The Forgotten Capital (or City of the Ancients) -
The city lies beyond the Sleeping Forest, past Bone Village, on the arctic of the Northern Continent.
The city was the capital & home to the Cetra civilisation, until Jenova (the calamity from the skies) caused the near-extinction of the Cetra.
Survivors integrated into human society, leaving the city abandoned in ruin - Eventually they died out & left just one - Aeris/Aerith.
There is a sad irony to this place.
I expect you already know.
/walks through wall.