 Ussishkin is an expert on the Iron Age of the Land of Israel.He has directed and co-directed important excavations at Lachish, Jezreel and Megiddo.In 1968–71 he undertook, with the assistance of his colleague Gabriel Barkay, the first complete survey of the Silwan necropolis rock-cut tombs of the Jerusalem First Temple period necropolis atop which the village of Silwan was built.