Archaeologists from the University of Tübingen in Germany unearthed the city, which lies beneath what is now the small village of Bassetki in the autonomous region of Kurdistan. Days after they completed the dig, Iraqi security forces began their push to take Mosul back from ISIS.
Measuring a kilometer in length and 500 meters across (about 1,000 yards by roughly 550 yards), the ancient urban area features grand houses, a palace, an extensive road network and a cemetery.
In making the discovery, the archaeologists solved a decades-old mystery relating to why a precious bronze statue of the Akkadian god-king Naram-Sin was discovered at the site by chance in 1975 during the building of a highway.
Until now, researchers were unable to explain the location of the find. The archaeologists have now been able to prove their theory that an important outpost of Akkadian culture was located in the Bassetki area.
The Akkadian empire, regarded as the first world empire in human history, existed in what is now Iraq, Syria and parts of southern Turkey from around 2340 to 2200 B.C.
"People always wondered why the statue came from this remote place. In 2013 we realized there is a large site from the early Bronze Age there," Prof. Peter Pfälzner, director of the Department of Near Eastern Archeology at the University of Tübingen, told CNN.
"It is actually not so rare that we find things like this -- this area is extremely under-explored, so surprises of this kind are to be expected."
The Bassetki statue, which dates from around 2250 BC, was stolen from the National Museum in Baghdad during the Iraq War in 2003, but later rediscovered by US soldiers. It is now back at the museum.
The dig, which involved about 30 people, began in August and finished in October.
The archaeologists were working to excavate the site as soon as possible because the original highway, which led to the discovery of the statue during its construction 41 years before, is being extended into a six-lane road. This was due to cut right across the site of the Bronze Age city.
"We were alarmed and of course wanted to immediately start excavations to demonstrate this to the local authorities," explained Pfälzner, who led the project alongside Dr. Hasan Qasim from the Directorate of Antiquities in Dohuk, a nearby town.
"We were surprised how cooperative they were when we had a meeting with the director of the planning office. We outlined the zone and they changed the track of the new highway, moving it around the site in a wide bow, so the site was rescued."
The city found at Bassetki is believed to have been established in about 3000 BC and to have existed for more than 1,200 years. It had a wall running around the upper part of the town in order to protect its residents from invaders, archaeologists found.
They also uncovered fragments of clay tablets with writing on them dating from about 1300 B.C., which suggested the existence of a temple dedicated to the Mesopotamian weather god Adad on the site.
Using geomagnetic resistance measurements -- a method of exploring what is beneath the ground without digging -- the archaeologists discovered indications of an extensive road network, various residential districts, grand houses and a palatial building.
The team stayed in Dohuk, which is just 60 kilometers north of Mosul. Despite the fact that Iraqi and Kurdish troops were preparing for the Mosul offensive as the team wrapped up, Pfälzner told CNN they felt very safe.
"In the Kurdish autonomous area in Iraq security is very high. This territory is unrisky to go to if you're prepared and you collaborate with the local authorities," he said.
The team hopes to return next year to do further excavations and research alongside their Kurdish colleagues, which they believe could continue for many years to come.
"I think the situation in the region (of the dig) will remain quiet and stable, and with the hopeful defeat of ISIS the situation might even become better," Pfälzner said.