This paper analyzes Seleucid urbanism in its role as an imperial tool and considers its impact on later Iranian traditions of city foundation and imperialism. The Seleucid urban network was a cornerstone of Seleucid empire-building and was the primary means by which the Seleucids imposed a new organizational, social, and symbolic regime on the former Achaemenid Empire. They functioned in aggregate as part of a larger systemic whole to project military power over and extract resources from the lands they controlled; however, this imperial system developed in new directions depending on the importance and fate of the foundation. Although the Seleucids were largely excised from later Iranian cultural memory, the colossal and creative efforts of the dynasty to reshape the remains of Achaemenid Persia into a new Iranian Empire made an equally profound impact on the development of the later Ira- nian world. The Seleucid period was a pivotal time of change, during which a new, encompassing imperial vision subsumed and supplanted Persian royal culture, and a stunning array of new royal cities eclipsed the old Persian loci of power, shifting Western Asia's poles of power toward the Tigris, Syria, and northern and eastern Iran. It set the stage for a new Iranian urbanism and via the Sasanians, was instrumental in the development of Islamic city.