Babylon, Egypt.

Biblical scholars have long taught that anytime you see Babylon referred to in early Christian scripture, it is a code word for Rome. They may be right, some of the time. However, in doing research for my Time Traveler’s guide to the 13th century, I’ve learned that old Cairo’s original name was Babylon, and there is a local local tradition that St. Mark, who did live in Egypt, wrote his Gospel in this city, not in Rome. I’ll save the rest of what I’ve learned for the chapter on visiting 13th Century Cairo.