I can’t find a good cite for the population before it happened (the best I got was around a million), but Nanking losing 300,000 people between December 1937 and February 1938 must be near some kind of record in terms of time frames.
The 2,000,000 citizens that were forcibly exacuated out of Phnom Penh by the Khmer Rouge on April 17/18, 1975, is still the winner in my book.
Varosha is completely abandoned and (was) quite modern.
Don’t forget Mohenjo-Daro and Harappa.
This fantasy of somehow getting in there and driving out a mint condition 1974 Lamborghini is quite a compelling one…
It doesn’t get much more mondo weirdo than this, folks.