I have chosen to group Nippur with Kish and Borsippa, as (1) they are geographically relatively close and (2) still present archeological remains of Sumeria. They are geographically more northern than the cities Uruk, Ur and Eridu (WHS Ahwar of Southern Iraq).
BUT (1) maybe they are thematically not adding anything new that is already present in the WHS "Ahwar of Southern Iraq" and (2) maybe they are too close to Babylon WHS, which is of much greater importance. On the other hand, maybe Babylon represents the ancient civilisation Babylonia more than it represents Sumer.
Full name of site: Sumerian cities of Lower Mesopotamia: Kish, Borsippa and
NippurCountry: Iraq
TWHS?: yes, partially: Nippur is a TWHS (see title)
Short description of site: (Wikipedia & Unesco) 1. Kish was an ancient tell (hill city) of Sumer in Mesopotamia. The Kish archaeological site is actually an oval area roughly 8 by 3 km (5 by 2 mi), transected by the dry former bed of the Euphrates River, encompassing around 40 mounds.
2. Borsippa: The ziggurat is today one of the most vividly identifiable surviving ones, identified in the later Talmudic and Arabic culture with the Tower of Babel. However, modern scholarship concludes that the Sumero-Akkadian builders of the Ziggurat in reality erected it as a religious edifice in honour of the local god Nabu, called the "son" of Babylon's Marduk, as would be appropriate for Babylon's lesser sister-city.
3. Nippur was among the most ancient of Sumerian cities. Nippur contains several layers of superimposed urban settlement extending from c. 5000 BCE to about 800 CE. The site encompasses a great complex of ruined mounds bisected from north to south by a deeply cut watercourse or canal, known locally as Shatt al-Nil.
Criteria: Cultural