Renowned excavator of Jerusalem’s Temple Mount and southeastern hill (1867-1870). In 1867 he was commissioned by the Palestine Exploration Fund (PEF) to study the features of Jerusalem’s historic structures. His investigations, heralded the development of stratigraphic excavation, are still of great value thanks to the careful plans and diagrams he provided, albeit achieved under extraordinarily difficult conditions. His findings were published in a volume co-edited with Claude R. Conder. Warren mapped the rock surface of the Temple Mount, as well as the water systems deriving from the Gihon Spring. He was the first to go through Hezekiah’s Tunnel. Warren’s publications include Recovery of Jerusalem (with C.W. Wilson), Underground Jerusalem and The Temple and the Tomb. He joined the PEF committee in 1871 and remained a member until his death.