The Cucuteni–Trypillia megasites in Ukraine appear to predate the Mesopotamian ones by a few centuries, though they didn't have writing (apparently).
I think that part of the reason the Cucuteni–Trypillia megasites are not mentioned so much in this context is because they look like enormous villages, missing many of the characteristics of a city which are present in Sumer.
Yeah there's other near east settlements of this sort going back a full 10,000 years. Sumer was the first with purpose-built monumental architecture.
these sites were in close proximity to the Vinca culture which did have some precursor of writing