The Fortress of Babylon

Babylon
The Fortress of Babylon was built as part of the Roman fortifications of the city of Memphis, on the outskirts of the ancient city of "On" (Heliopolis). The fortress lay on the eastern bank of the river at that time, but the Nile shifted westward, leaving the area of Old Cairo further east of the river. The original fortress city was founded around 30 BC - the year the emperor Augustus entered Alexandria. The Romans brought Christianity to Egypt in the 1st century AD, and the city of Babylon became known as a centre of the new religion, a safer place for Christians in times of conflict than Alexandria in the north. It was built on the outskirts of an even older city, Heliopolis, an important religious centre throughout the history of the Egyptian pharaohs, also known as "On" in biblical times. The new fortress was built in the 2nd century by the emperor Trajan, and these are the remains you can see today. Of the riverside ramparts of Trajan, only the southern part of the tower remains; excavations have revealed parts of the quay below the modern street level.
The origin of the name "Babylon-in-Egypt" is unclear, but it is suggested that it comes from "Per-hapy-en-On" (Nile house of On). Old Cairo is known as Misr el-Qadima, and visitors to the courtyard can see the remaining restored towers of the Babylon fortifications of Trajan, opposite the Mar Girgis (St George) metro station and the secondary entrance to the Coptic Museum.
The word "Coptic" derives from the ancient Egyptian language and was used to describe the early Christian religion in Egypt, in the transitional period between the times of the pharaohs and the Islamic era. The Coptic Orthodox Church was very important for many centuries and remains the second religion in Egypt to this day. Numerous churches and monasteries were built in the old quarter of Cairo, which is still considered a holy place by Copts. Legend has it that the Holy Family rested here in a cave when they came to Egypt.
There are many Coptic churches to be seen in Old Cairo, above all the "Hanging Church" (el-Moallaqa). This is the nickname of the Metropolitan Church of St Mary the Virgin, built on the site of Babylon in the 4th century AD; on the upper right you can see the gate of the Roman fortifications, with its nave suspended over the passage of the gatehouse. It is said to have been one of the first churches in the world to hold Coptic rituals. It has seen many changes, most recently in the 19th century, when a fourth aisle was added to the original structure. The three original shrines were dedicated to the Virgin Mary, St John the Baptist and St George. The Hanging Church is actually entered through the courtyard of the Coptic Museum. The nearest Old Cairo churches include those of St Sergius and Bacchus (the oldest church in Cairo), the monastery and church of St George, and the church of St Barbara. Many old churches can only be visited with permission.