Nineveh

Nineveh, also known in early modern times as Kouyunjik, was an ancient Assyrian city of Upper Mesopotamia, located in the modern-day city of Mosul in northern Iraq. It is located on the eastern bank of the Tigris River and was the capital and largest city of the Neo-Assyrian Empire, as well as the largest city in the world for several decades. Today, it is a common name for the half of Mosul that lies on the eastern bank of the Tigris, and the country's Nineveh Governorate takes its name from it.

It was the largest city in the world for approximately fifty years until the year 612 BC when, after a bitter period of civil war in Assyria, it was sacked by a coalition of its former subject peoples including the Babylonians, Medes, and Scythians. The city was never again a political or administrative centre, but by Late Antiquity it was the seat of a Christian bishop. It declined relative to Mosul during the Middle Ages and was mostly abandoned by the 13th century AD.

Source: Wikipedia