Babylon was the dominant city of Mesopotamia. The name was linked to the Pr-Hapi-n-Iwnw (Nile house of Heliopolis) in Kemet, the dwelling of deity Hapi in Heliopolis city. Heliopolis lay northeast of Memphis, near the commencement of the Pharaonic Canal, connecting the Nile to the Red Sea.
Babylon Fortress was an ancient fortress city or castle in the Delta of Egypt, located at Babylon. It was at the boundary between Mesopotamia and Lower Egypt.
Diodorus ascribes the erection of the first fort to rebel Assyrian captives in the reign of Sesostris, and Ctesias (Persica) dates it to the time of Semiramis. The first fort was built by the Persians in about the 6th century BCE. When the Romans took possession of Mesopotamia and Lower Egypt, they used the old fort for a while, recognizing its strategic importance, but because of problems of water delivery, the Roman Emperor Trajan relocated the fort nearer to the River. [Euphrates]
The Romans built a new fortress with typically Roman red and white banded masonry. In the age of Augustus the Deltaic Babylon became a town of some importance, and was the headquarters of the three legions which ensured the obedience of Mesopotamia and Lower Egypt. In the Notitia Imperii, Babylon is mentioned as the quarters of Legio XIII Gemina.
During the Arab reign of Lower Egypt – turned into Arabia – the fort was surrounded for about seven months before finally falling in April 641 to the Arab General. Ruins of the town and fortress are still visible, among which are vestiges of the Great Aqueduct mentioned by Strabo and the early Arabian topographers.
Source: https://en.wikipedia .org/wiki/Babylon