The oldest religious quarter of Cairo is not Fatimid at all. Around the Roman fortress of Babylon, south of the medieval city, stand churches that were old before the Arab conquest: the Hanging Church suspended over a gatehouse of the fortress, and Abu Serga, beneath which a crypt is venerated as a shelter of the holy family during the flight into Egypt. That tradition of the flight is the reason a series of Egyptian sites is a pilgrimage route for Copts, and it is one of the few strands of the gospel narrative that gives Egypt a place in it.
The Coptic Orthodox Church traces its see to Mark the Evangelist at Alexandria and now has its papal seat in Cairo. It is the largest Christian community in the Middle East, and its liturgy preserves the Coptic language in a country that has spoken Arabic for over a thousand years.
Inside the same quarter is the Ben Ezra synagogue, whose lumber room produced one of the great documentary finds of any tradition. Jewish practice forbids the destruction of writing that carries the divine name, so worn out books and papers were stored in a geniza. The Cairo geniza was never cleared, and by the nineteenth century held several hundred thousand fragments, dispersed to European and American libraries in the 1890s, most of them to Cambridge through Solomon Schechter. They include lost Hebrew works, early copies of rabbinic texts, and above all the ordinary paperwork of medieval life, letters, accounts, marriage contracts and shopping lists, from which S. D. Goitein reconstructed a whole Mediterranean society.