31.322222N, 45.636111E East of the present bed of the Euphrates river on an ancient dry former channel of the river
"Uruk played a leading role in the early urbanization of Sumer in the mid 4th millennium BC. At its height c 2900 BC, Uruk probably had 50,000–80,000 residents living in 6 km2 of walled area; making it the largest city in the world at the time (Harmansah). Uruk was famous as the capital city of Gilgamesh, hero of the Epic of Gilgamesh. It is also believed Uruk is the biblical (Genesis 10:10) Erech, the second city founded by Nimrod in Shinar (Ball). In addition to being one of the first cities, Uruk was the main force of urbanization during the Uruk period (4000–3200 BC). This period of 800 years saw a shift from small, agricultural villages to a larger urban center with a full-time bureaucracy, military, and stratified society."(Wikipedia)
Approximate Year of Completion
Stopped major growth phases in about 3100 BC at the end of the late Uruk period.
Duration of construction
about 4000 BC to 3100 BC
The settlement measures 6 km2 (2.3 sq mi). The project invoked literally building a huge and intricate city, so I have decided to focus on the really interesting things like the temples and recurring architectural themes and explain them in Construction Details.
There were two main types of sumerian architecture present in the structures of Uruk. The tripartite plan inherited from the Ubaid (the period in time before the Uruk period) had a large central hall with two smaller flanking halls on either side (demonstrated in A below). The entry was along the short axis and the shrine was at the end of the long axis. The T-shaped plan, also from the Ubaid period, was the same as the tripartite plan except for a hall at one end of the rectangle perpendicular to the main hall (demonstrated in C below).
Adobe brick was used for many of the buildings in Uruk. “The building of adobe and soil wall is very old in the history of humanity. Thousands of years old adobe wall building and building residuals remained for us. Not only the thermo balancing ability adobe wall is very good, but its humidity balance attribution as well. The adobe wall, if it becomes properly dry, then very hard, enduring, and capable of carrying weight. The one enemy of this structure is the water. Because of the effect of much humidity, it lose its stability” (Á. Nemcsics and A. Ürmös)
Natural bitumen deposits were used in Uruk for mortar between limestone blocks on a few special temples. While adobe brick use was far more common, it should be noted that at least two temples and one other building built in between 4000 BC and 2000 BC used this limestone and bitumen method.
Other significant comments
I think it is really important to note again that Uruk was one of the first major cities ever. Uruk changed the way that people lived, having them come into the cities rather than live entirely independent elsewhere.