Around 3100 BC, Uruk was probably the largest city on Earth
Uruk, now the ruin mound of Warka in southern Iraq, may have housed up to 50,000 people at its peak, with tens of thousands more around it. Laced with canals nicknamed Venice in the desert, it was home to Gilgamesh and may even have given Iraq its name.
The ruins lie in Iraq's Muthanna Governorate, east of today's Euphrates on a long-dry former channel, 93 km northwest of ancient Ur and 24 km northwest of Larsa. The city originally stood southwest of the river; a later shift in the Euphrates, together with salt building up in irrigated fields, may have helped bring about its decline. Its names range from Sumerian Unug to Arabic Warka and Biblical Hebrew Erech, and many linguists think the word Iraq descends from it.
Uruk grew from two small Ubaid villages that became the towns of Unug and Kullaba and then fused. Their temple cores became the Eanna precinct, sacred to Inanna throughout the city's life and walled off around its workshops, and the Anu precinct, whose temple crowned a raised terrace. Ordinary courtyard houses clustered by trade around the two, and canals connected every quarter to Euphrates shipping and the surrounding farmland. During the Uruk expansion of 4000 to 3200 BC, an 800-year span, small farming villages gave way to a city with a full-time bureaucracy, an army and social ranks, and Sumerian traders and colonists carried its culture to neighbouring peoples.
Tradition names Enmerkar as the founder and builder of Inanna's House of Heaven, and the Epic of Gilgamesh credits Gilgamesh with raising the city wall; the Sumerian King List puts his reign in the 27th century BC, though historians treat that list's accuracy with caution. After the Akkadian Empire absorbed it, Uruk declined, revived under Ur with a new ziggurat for Inanna, then slumped again after Ur fell around 2000 BC until the Neo-Assyrians made it a provincial capital about 850 BC.
The late centuries were surprisingly grand. The Bīt Reš temple, added by 250 BC, was one of the two main centres of Neo-Babylonian astronomy. Under the Seleucids, who knew the place as Orcha, it covered 300 hectares with perhaps 40,000 inhabitants, and its rebuilt Anu ziggurat was the largest ever raised in Mesopotamia. It carried on after the Parthians took over in 141 BC but was largely deserted by 300 AD.
Source: Uruk