Several of their oldest churches are built into or on its walls. These include El-Muallaqa (the Hanging Church) and the Greek Church of St. George. A number of other Coptic churches are nearby. The area is called Old, or Coptic Cairo (Masr el Atika), for this is indeed the oldest part of the city, and the remains of the fort are Cairo proper's oldest original structure. Indeed, Cairo owes its existence to this fort.