This thesis attempts to give the increasing importance of Ottoman port cities in the urban hierarchy during the nineteenth century and analyzes the urban transformation of these cities under the forces of changing administrative and socio-economic structure of the empire. The impact of European economic penetration and Ottoman Tanzimat Reforms were indicated as major causes for this changing structure. Beirut, being one of the major port cities of the Ottoman Empire is studied as a case study. The changing administrative and socio-economic structure of the Empire created an urban transformation which changed the city to a cosmopolitan trade capital from a small fortified port city.