Three seasons of excavation at Tell Abu Shahrain, the site of ancient Eridu, were carried out by the Iraqi Directorate General of Antiquities after the Second World War under Fuad Safar, with Seton Lloyd and Mohammad Ali Mustafa. The excavators cut down through the mound beneath the unfinished ziggurat platform and found a series of temples built one directly above another on the same spot.
The earliest is a small single room structure near the base. The latest is a substantial building under the later platform. Between them the sequence repeats two features across rebuild after rebuild: an offering table and a niche, in the same relation to one another and in the same place.
That repetition is what makes the result so widely cited. It is the strongest physical case anywhere in Mesopotamia for cult conducted in one spot over a very long span, and it is regularly invoked in general accounts as showing a sanctuary rebuilt on its own ruins from the beginning of settlement on the southern plain. The final report appeared decades after the fieldwork, in 1981.
Eridu's standing in the later Mesopotamian tradition gives the find additional weight. The Sumerian King List names Eridu as the first city, the place where kingship first descended from heaven, and the god Enki is its lord in the literary tradition. An excavation that turns up a deep stack of temples at exactly the site later Mesopotamians treated as the oldest of all is a striking convergence between text and ground, and that convergence is a large part of why the sequence is cited so often.