Sparta, ancient Corinth (modern town is on a different site), Rome (has undergone revival since its nadir), Timbuktu, Niya, Petra (all former trade nodes), Samarkand (Tamerlane's capital), Aquilea (destroyed several times, most notably by the Huns), a couple of dozen Mayan etc. cities abandoned for unknown reasons in the precolumbian era, about a million major mining towns that went downhill when the ore ran out, lumber towns when ditto...

Maybe you could narrow it down a bit? Are we talking 20th C only, including cities destroyed by war?