She was a city, once.
The Alterans leave Atlantis in dribs and drabs, a corridor here and a tower there, until a scant handful remains. After a few months it seems almost normal; if they stay inside, they can pretend everyone else is still there, and they do for a while, until it’s no longer a joke.
(She knows better, though: their few life signatures fill her vastness like a handful of coals in the ashy hollow of a burnt-out bonfire.)
Slowly, system by system, they shut her down, until all that’s left is a sleeping shell buried beneath the ocean, dreaming of the sky.