Of the various Hellenistic kingdoms which arose out of the dissolution of Alexander the Great's dominions, and most resembled the empire conquered and for a time ruled over by the Macedonian king, was the Seleucid kingdom. This chapter discusses the geographical description, and military and naval aspects of the Seleucid Kingdom. The organization of the official cult of the sovereign can be useful for tracing the Seleucid administrative divisions. In considering the relations between the Seleucid kingdom and the Greek cities one must distinguish between the new Seleucid foundations and the 'old cities' which existed before the Seleucid period and even before that of Alexander and the Diadochi. The precise role of the Iranian regions and policies pursued there by the Seleucid sovereigns are less clear in comparison with the Persian empire, and the axis of the Seleucid kingdom was markedly further to the west. The achievement of Seleucid Syria is to be assessed historically as a posthumous contribution.