Isis recently destroyed an ancient wall of Mosul in Ninevah, widely considered to be one of the most cherished hisorical landmarks in Iraq. What historic value does the wall have? What were the people like who built it?

I'll give you the best answer that I can without violating the 20-year rule here. Keep in mind that we have as yet fragmentary reports of what was destroyed.

Now, a note on clarity. The ancient city of Nineveh is located on the eastern bank of the Tigris River in Northern Iraq. It is separate from Mosul proper, though the growth of that city has encroached upon the ancient site. There are multiple contradictory accounts of what has been destroyed since Daesh/ISIS/ISIL captured the site in June.

The Nineveh archaeological site includes two large mounds, one of which included a shrine/mosque to the Prophet Jonah (Yunus). That site was blown up by Daesh in July. The other mound has been excavated to a great degree. Near and to some extent surrounding these mounds are the remains of a stone and mud-brick wall that is believed to be about 2,600 years old, give or take a few centuries. The most prominent aspects of this wall are a series of gates.

That word doesn't adequately describe them, however. These gates were designed to be monuments, barracks and armories, as well as access control points to the ancient city. Most have been surveyed and excavated since the 19th century, and the Iraqi government made some attempts to restore the gates to varying degrees.

How important is Nineveh? Well, surveys have shown that the site of the city has been home to human habitation for at least 8,000 years. It was the royal capital of the Assyrian Empire, and it appears in several books of the Bible. Starting in the 19th century, it was explored and excavated. These excavations uncovered the Library of Ashurbanipal, whose clay tablets were an important source of information on early life in the Middle East before cataloging errors mixed everything up. It is said that this library was the inspiration for the Library of Alexandria.

Nineveh is believed to have been largely abandoned about 600 BC, following the conquest of Assyria by a coalition of competing empires. It remains an important archaeological site, and it is on the UNESCO World Heritage Site waitlist.