Ashur (Qal'at Sherqat)

On the Tigris, where rain-fed farming gives way to irrigation, Ashur served as first capital of the Assyrian Empire between the 14th and 9th centuries BC and remained its religious heart, home of the god who shared the city's name. Founded in the 3rd millennium BC and long an international trading city-state, it fell to the Babylonians, then revived under the Parthians in the 1st and 2nd centuries AD. UNESCO inscribed Ashur in 2003.