Cairo's Coptic Christian neighborhood
There are two old parts of Cairo, the Coptic Christian neighborhood and the Islamic neighborhood (known as Old Islamic Cairo). The former is a pedestrian-only area which you can access via the Mar Girgis metro station. There's a lot of security on Saleh Salem Street and there's usually a police checkpoint with a metal detector; if you go by the metro, you won't have to deal with it. The points of interest include the third century Hanging Church with its beautiful icons from the eighth to eighteenth centuries, the ruins of the Roman Bablyon Fortress, the Greek Orthodox church of St. George, and several lesser churches.