Babylon Fortress (Arabic: حصن بابليون; Coptic: ⲡⲁⲃⲓⲗⲱⲛ or Ⲃⲁⲃⲩⲗⲱⲛ) is an ancient fortress in the Nile Delta, located in the area known today as Coptic Cairo. It is situated in the former area of the Heliopolite Nome, upon the east bank of the Nile, at latitude 30°N, near the commencement of the Pharaonic Canal (also called Ptolemy's Canal and Trajan's Canal), from the Nile to the Red Sea.

It was at the boundary between Lower and Middle Egypt, where the river craft paid tolls when ascending or descending the Nile. Diodorus ascribes the erection of the first fort to rebel Assyrian captives in the reign of Sesostris, and Ctesias dates it to the time of Semiramis; but Josephus, with greater probability, attributes its structure to some Babylonian followers of Cambyses, in 525 BC. The Romans built a new fortress nearer the river, with typically Roman red and white banded masonry.