Saint Mercurius Church is located in the heart of old Cairo, north of the Babylon Fortress, known as Abu Sayfayn Cloister. it was built in the 6th century and underwent intensive restoration during the 12th century, dedicated to Saint Philopater Mercurius. The Church of Saint Mercurius served as the Seat of the Coptic Orthodox Pope of Alexandria between 1300 and 1500 AD and it stands 31.5 meters long by 21 meters wide.
Saint Mercurius church was destroyed and converted to a sugarcane warehouse, but Patriarch Abraham rebuilt it again, and then in 1080, the Fatimid Badr Al-Gamal ordered 47 bishops to construct the Coptic canons. Like many other old Coptic Orthodox churches that were rebuilt and restored time and again over the centuries,often re-using wood and stone-work. For this reason some parts of a church maybe of earlier date than the structure itself. Although they differ in size and architecture features they bear the unmistakable stamp of a Coptic church.