The extraordinary feats of conquest of Cyrus the Great and Alexander the Great have left a lasting imprint in the annals of world history. Successive Persian and Greek rule over vast stretches of territory from the Indus to the eastern Mediterranean also created an international environment in which people, commodities, technological innovations, as well as intellectual, political, and artistic ideas could circulate across the ancient world unhindered by ethno-cultural and territorial barriers, bringing about cross-fertilization between East and West. These broad patterns of cultural phenomena are illustrated in twenty-four contributions to the first international conference on ancient Greek-Iranian interactions, which was organized as a joint Greek and Iranian initiative.