The product of a decade of research, The Iranian Expanse is a study of the natural and built environments of power in Persia and the ancient Iranian world from the consolidation of the Achaemenid Empire in the sixth century BCE to the fall of the Sasanian Empire in the seventh century CE. It analyzes the formation and development of some of the most enduring expressions of power in Persia and the ancient Iranian world: palaces, paradise gardens and hunting enclosures, royal cities, sanctuaries and landscapes marked with a rich history of rock art and ritual activity. It explores how these structures, landscapes and urban spaces constructed and transformed Iranian imperial cosmologies, royal identities, and understandings of the past. While previous studies have often noted startling continuities between the traditions of the Achaemenids and the art and architecture of medieval or Early Modern Islam, they have routinely downplayed or ignored the tumultuous millennium between Alexander and Islam. The first study of its kind, the Iranian Expanse shows how the Seleucids, Arsacids and Sasanians played a transformative role in the development of a new Iranian royal culture that impacted early Islam and the wider Persianate world of such dynasties as the Il-Khans, Safavids, Timurids and Mughals.