Calah in the Bible.

What happened at Calah.

One of the most ancient cities of Assyria. “Out of that land he [i.e., Nimrod] went forth into Assyria, and built Nineveh, Rehoboth-Ir, and Calah, and Resen” (Gen. 10:11, R.V.). Its site is now marked probably by the Nimrud ruins on the left bank of the Tigris. These cover an area of about 1,000 acres, and are second only in size and importance to the mass of ruins opposite Mosul. This city was at one time the capital of the empire, and was the residence of Sardanapalus and his successors down to the time of Sargon, who built a new capital, the modern Khorsabad. It has been conjectured that these four cities mentioned in Gen. 10:11 were afterwards all united into one and called Nineveh (q.v.).

From Easton’s Bible Dictionary (1897).