Mons Porphyrites, in the heart of the Red Sea mountains which dominate the Eastern Desert of Egypt, was the only source of imperial porphyry known to the ancient world. The quarries seem to have been worked from the Tiberian period until the early fifth century AD. A five-year programme of investigation of the quarries was undertaken between 1994 and 1998. This second volume of reports of that programme provides details of the excavations and a review of the overall development of the quarry complex. It maps out six distinct quarrying areas, recording ancient Roman quarrying methods, infrastructure, and the distribution of imperial porphyry stone.