Uh, Nineveh was the capital of the Assyrian Empire. The Assyrian’s and the Babylonians were arch enemies for hundreds (thousands?) of years. The city of Babylon ended when the Assyrian Empire killed everyone in the city, burned every building, diverted a river over the ruins, and then salted the earth and seeded what remained with thorny and poisonous plants. Saying that the Hanging Gardens of Babylon were really in Nineveh is like saying that the Statue of Liberty was actually in Moscow, the Colosseum was really in Carthage, and the Eiffel Tower was actually Berlin.
I’m not saying that this archaeologist is wrong, just that it seems like a pretty large oversight in history if the Hanging Gardens of Babylon were really in the capital of their arch nemesis that would eventually erase Babylon, one of the greatest cities of the old world.