BERLIN (AP) — Berlin's Pergamon Museum is offering visitors a glimpse of perhaps the world's first real metropolis in a new exhibition that traces the long history of Uruk, in present-day Iraq.

Artifacts, including clay masks of demons, figurines of rulers, limestone ducks used as weights, a prism listing Sumerian kings and clay vessels used as water pipes, grace the exhibition "Uruk — 5,000 Years of the Megacity." They date back as far as the 4th millennium B.C.

The show marks a century of excavations at Uruk in which German experts have played a prominent part. But even now, organizers say, less than 5 percent of the sprawling site in the Iraqi desert about 260 kilometers (160 miles) south of Baghdad has been explored.

Michael Eissenhauer, the director of Berlin's city museums, said Wednesday the exhibition aims to illustrate the importance of Uruk, "the first identifiable major city in the history of mankind" — believed to have had about 40,000 inhabitants in the 4th millennium B.C. and city walls more than 9 kilometers (5 1/2 miles) long.

It was in Uruk where "highly developed organizational forms of city life were developed," with writings and archives among the things discovered there, Eissenhauer said. "Uruk is the cradle of a sophisticated economic and administrative system."

The exhibition includes clay tablets detailing agreements and transactions, such as a payment in silver for delivering valuable stones, and a fragment of an early administrative text.

Uruk is commemorated in the epic poem of Gilgamesh, written on clay tablets about 2,000 B.C. and telling story of a legendary king. A figurine of Gilgamesh features in the exhibition.

The pieces on show at the Pergamon Museum, which is also home to Babylon's famous Ishtar Gate, include items from collections in Berlin and Heidelberg as well as pieces on loan from London's British Museum, Paris' Louvre and the Ashmolean Museum in Oxford, England.

Organizers hoped to secure exhibits from Iraq, but the idea fell apart because export permits would have needed the approval of the entire Iraqi Cabinet. That "is not feasible in the current political circumstances," Margarete van Ess of the German Archaeological Institute said

The exhibition opens to the public Thursday and runs through Sept. 8.