Greater Cairo is a megalopolis with nearly 17 million inhabitants. As the city has few green spaces, in 1998 the Aga Khan Trust for Culture (AKTC) launched a project to create a new panoramic park at the edge of historic Cairo. In 2000, a scientific cooperation was established between the Egyptian Ministry of Antiquities, the French Institute of Oriental Archaeology (IFAO), and the AKTC to excavate and document the archaeological sites along the al-Azhar Park. From 2001 to 2009, the main archaeological site was the Darrāsah parking lot, also called the “Archaeological Triangle.” This site is remarkable for its location in the city, less than 350 meters east of the al-Azhar mosque and along the Fatimid and Ayyubid city walls. Eight missions, totalling 18 months of excavations, were carried out on this site. For historians, Cairo is one of the best known and most well documented Middle Eastern cities during the medieval period, as it was the capital of several important dynasties, including the Fatimids, Ayyubids, and Mamluks. Mamluk Cairo faced a series of epidemics of plagues and the Black Death from the fourteenth until the fifteenth century and later. These plague epidemics were described in detail by historians but have never been observed physically. Our archaeological excavations have revealed this tragic story through a unique source of documentation: the cemetery of Bāb al-Ghurayb.