Although many ancient cities have been abandoned or lost, only a few have truly disappeared from human knowledge. Herculaneum and Pompeii, buried by Vesuvius in 79 AD, were discovered in the 18th century after years of excavation.

Other lost cities, such as Petra and Tim Gad, were hidden from European scholars due to their remoteness. Despite decades of surveys and aerial photography, there are still a handful of ancient cities that remain truly lost. Many ancient cities are known but unexcavated due to inaccessibility or inadequate funding.

Pompeii and Herculaneum are only partly excavated, and the suburbs, villages, and villas that surrounded them are largely unexplored. Chance discoveries have revealed dozens of elaborate Roman villas in the districts north of Pompeii, and many other villas in the vicinity await rediscovery.

The town of Murin, a suburb of Pompeii, has only sporadically produced discoveries such as a sprawling villa with a private bath and the archive of the Suiki. The smoking pits and fumeroles of the Phlegraean Fields, across the Bay of Naples from Pompeii and Vesuvius, have also claimed ancient settlements. The ruins of these settlements are buried under unknown depths.