Pick a lost or abandoned city. Set the story there, but maybe not in its last days.
Atlantis, Port Royal, Pompeii, Machu Picchu, Helike, Camelot, El Dorado, Troy, Songo Mnara, Angkor, Great Zimbabwe, Tikal, pick a place and run with it. Or write about sunken New Orleans, the lost city of Tokyo, or the tiny towns being blown away as the plains become the deserts.
(Yes, this is an ambitious writing prompt. You may want to consider this one for the next story you write. Either way, have fun with it.)