The Cincinnati Art Museum's Petra exhibit not only gives museum-goers a multimedia experience of an extraordinary World Heritage Site, but the haunting story of that long-lost city of stone communicates across the centuries that cities need to adapt to shifting world commerce.

The Petra show runs today through Jan. 30. It is a huge coup for the Cincinnati Art Museum, which collaborated with the American Museum of Natural History in New York to bring this cultural exchange from Jordan to the states. Hundreds of thousands saw Petra's treasures in New York. Crowds here will find much more than the movie location for Indiana Jones and the Last Crusade.

Petra isn't just for architecture or archaeology students, stone carvers or world travelers. It also should be mandatory study for city planners, neighborhood groups and entrepreneurs.

More than 2,000 years ago, a wandering Arab tribe known as the Nabataeans made an unusually rapid switch from nomadic trading to city-dwelling. By 200 B.C. they were carving a fabulous city out of rose-red sandstone cliffs in the desert and engineering one of the most advanced city water-supply systems in the ancient world. For at least 400 years they built one of the wealthiest cities in the world at the nexus of the silk and spice trading routes between Rome, Greece, India and China.

But by the 6th century A.D., Petra had faded, and for more than 1,000 years its narrow-gorge access-way was lost to history - until 1812, when Swiss explorer Johann Burckhardt "rediscovered" it. In 1932, Cincinnati archaeologist Nelson Glueck excavated the Nabataean sanctuary at Khirbet et-Tannur. His work accounts for the fact that the Cincinnati Art Museum owns the most distinguished collection of Nabataean sculpture outside Jordan.

What happened to the Nabataeans? They didn't or couldn't adapt to two profound jolts - one commercial, the other, an act of God. Their wealth derived from trade caravans, some 2,500 camels long. Roman shipping shifted those land routes to the seas. Then in 363 A.D., an earthquake destroyed much of the city. Petra lacked the will or wherewithal to rebuild.

That one-two punch would be like Greater Cincinnati losing the Brent Spence Bridge and the airport's Delta hub, and then getting hit with a tornado. Crossroads cities must constantly rebuild and adapt or they die. They also need to recognize that unless private commerce generates new revenues, cities will decline even if some of their grand art survives.