In Tablet I of the The Epic of Gilgamesh, Seven Sages are said to have laid the foundations of Uruk:
Climb Uruk's wall and walk back and forth!
Survey its foundations, examine the brickwork!
Were its bricks not fired in an oven?
Did the Seven Sages not lay its foundations?Source: The Epic of Gilgamesh, translated by Andrew George, Penguin Books
Who were they?
The Seven Sages are the Apkallu.
The Dictionary of Deities and Demons in the Bible states that they were servants of Ea, responsible for teaching mankind how to govern and start civilization. They interacted with the ancient kings1, and Gilgamesh is referred to in one "cylinder" as "master of the Apkallu". Additionally,
the seven Apkallu became associated with laying the foundations of the seven ancient cities: Eridu, Ur, Nippur, Kullab, Kesh, Lagash, and Shuruppak.
The entry then confirms that the Apkallu are the Seven Sages mentioned in The Epic of Gilgamesh.
The Assyrian Sacred Tree: A History of Interpretations states that certain depictions of the Apkallu show them having the heads of birds, as well as having wings.
It is possible that the reason the city of Uruk is not included in that entry is that the author of The Epic of Gilgamesh simple borrowed the idea of the Apkallu from other, perhaps earlier, works, and thus it is not consistent with the classical accounts of them.
1 Another book explicitly says that only one Apkallu advised each of seven ancient kings; each one advised in a different "generation", although this does not imply that the Apkallu are related to one another as parents to children. This entire claim differs slightly from other interpretations.
Short answer.
The sources for these are in the Perspectives on Language and Text: Essays and Poems in Honor .
Each if these sages are said to be responsible for the building or the laying of the foundations of the following cities in Uruk
Shuruppak
Ur
Kesh
Kullab
Eridu
Nippur
Lagash
