Mosul, Iraq.
More than two-and-a-half thousand years ago, this city - then known as Nineveh - was the capital of Assyria, which ruled much of the modern Middle East.
The Assyrians built the first huge empire in the history of humankind.
They excelled at science and engineering... revolutionized warfare... and created one of the world's first great libraries.
In many ways the Assyrians are the beginning of the modern world.
[Speaking Arabic] [Speaking Arabic] But during three years of occupation, the Islamic State - or Daesh, as it is also known - destroyed many of the citys Assyrian treasures.
[Speaking Arabic] Now, archaeology is fighting back.
It's amazing because, at first, we thought that here would be nothing.
Daesh wreaked destruction... ...but what remain is revealing the most complete picture of ancient Nineveh ever.
The tunnels are going in all direction.
You know, here's a tunnel, theres a tunnel.
Archaeologists are unearthing new discoveries... [Speaking Arabic] [Speaking Arabic] ...reconstructing the city's past... A lot of pieces, one million, two million.
We have a lot of pieces.
...and investigating an ancient mystery.
Could Nineveh be the hom to a lost Wonder of the World?
The Hanging Gardens of Babylon.