Babylon.
The Tigris and Euphrates rivers were assets to the early peoples of Sumer. They remain important rivers to this day.
Fertile Crescent.
It is located on the banks of the Euphrates
It was the area of modern Iraq. They became empires. First were the Sumerian followed by the Assyrians. The capital was the city of Nineveh. Then came the Babylon empire which the city was the capital.
No. Alexandria was a city named after Alexander the Great. It became the capital of ancient Egypt after the Ptolemies took over. It was never an empire, just the capital city of one.
Tenochtitlan was the capital city and religious center of the Aztec Civilization
While there was no official "capital" (because of the multiple empires that come and go), one of (if not the) most important trade city in West Africa was Timbuktu.
Edo
The ancient city of Ur was founded on the banks of the Euphrates River
Mexico City is built upon the remains on Tenochtitlan, the Aztec capital from the 1300s to the early 1500s.
Istanbul is a city itself not a country, is it does not have a capital. However, it used to be the capital of Ottoman and Byzantine Empires consecutively. After the Republic of Turkey was established the capital of the new republic was moved to Ankara, so Istanbul currently is not a capital of any country either.
The Nuprigan River and the Tigariha River.