World’s first city that wasn’t submerged by the glacier melts.
Well, yeah. :^) The Sumerians considered Eridu the first city in that region, but Samuel Noah Kramer pointed out that the place names (cities and rivers) of the Sumerians didn’t have Sumerian names. The Sumerians preserved the place names and hence recorded small fragments of whatever language had been spoken in Mesopotamia before their arrival. The rest of the language is unrecorded and presumably will remain unknown.
The Sumerians thought all cities were founded by the gods, a superstition which may account for their reluctance to a) found cities of their own and b) rename stuff.
submerged city example in India:
https://en.wikipedia.org/wiki/Dv%C4%81rak%C4%81#Submergence