This study addresses issues that pertain to the urban transformation of the builtenvironment of a pre-colonial city of the Indian sub continent following British occupation. The research centres on the city of Shahjahanabad / Old Delhi as the recipient of change that transformed the architecture and urban form of the 17`h century city built by the Mughals to conform to the British vision of urbanism shaped by political needs and belief in the superiority of European civilization. The study extends the past scholarship on the city by presenting a total picture of Shahjahanabad / Old Delhi's built-environment and the transformation of its urban form at macro and micro levels as one culture made way for the next. The study acknowledges the presence of political considerations, both in their direct manifestation and as an undercurrent, in all architectural interventions, given the colonial relationship between the city and its British occupants. The Mutiny was the fulcrum about which two architecturally distinct approaches towards addressing the city's urban form can be discerned. The year 1911, when the politically significant decision to transfer the capital of British India to Delhi was announced, also had a bearing on the relationship between the British and the city. As the British attention was diverted towards building New Delhi interventions in the older city, now referred to as Old Delhi, were directed to make it a presentable neighbour of New Delhi. The study explores how British architecture, planning and urban design inputs contributed towards the creation of a British identity, in the backdrop of the political climate, by transforming the urban landscape of 17th century Shahjahanabad from the early I 9th century to the early 20th century. It is concluded that the degree of interventions made in the built-environment of Shahjahanabad / Old Delhi was the outcome of contemporaneous political developments. The interventions were directed to make Shahjahanabad / Old Delhi habitable for the resident European community and to create a British identity. The study draws attention to the difference in the pre-Mutiny and post- Mutiny architectural scenario as well as to the post-1911 neglect of the city. The following themes are scrutinised in a chronological sequence: (i) the development of the built-environment of Shahjahanabad under the Mughals, from Emperor Shahjahan and his successors, till its British occupation, (ii) the British response to Delhi's Mughal institutions and built-form types as rulers of the city and subsequent introduction of European institutions to forge their own identity in an alien cultural milieu. This is discussed as two distinct sets of reactions underpinned by the Mutiny, as in pre-Mutiny and post-Mutiny scenarios, (iii) the contributions of the institution of the durbar (court) with its transient trappings of ceremony, festivity and cardboard architecture as harbingers of a permanent identity, (iv) the building of a new capital as a symbol of the permanence of British Raj (rule) and the concomitant diversion of attention to the New Delhi project leading to the neglect of Shahjahanabad / Old Delhi. The outcomes of this research, based on the interpretation and description of empirical data and documentary sources, are presented in two parts. Part-I builds the picture of the city at the macro level as it traces the evolution of the builtenvironment of the city as a whole. Part-II delves into the city fabric to present the micro level architectural scenario as it examines case studies of various built-form precincts whose urban form was transformed following British intervention.