Indigenous architecture of the Yorubas documented over time have mainly been limited to the traditional and vernacular expositions with the morphology traced from the earliest structures and not explicit beyond the Afro-Brazilian style. The morphology of the indigenous buildings has progressed organically, based on the socio-cultural changes in the society. This progression is however prone to more rapid changes that tend to direct it towards building patterns from other cultures. Urban upgrades are common in city cores of Nigeria where the legacy of indigenous building patterns is most preserved within the urban setting. Abeokuta in southwest Nigeria has been highly reported in recent times as having witnessed urban upgrades that have led to very rapid changes in its socio-spatial environment. This study set out to investigate the impact of the urban upgrades carried out in the city core of Abeokuta between 2009 and 2018 on the forms and elements of the indigenous building morphology. This was done by tracing the morphology of the indigenous building pattern from the advent of settlements in the area till the study period as the first objective. Areas where urban upgrades have been carried out were identified and new building typologies that are evolving in the areas were analysed for changes in their forms and elements as different from the threshold of indigenous building morphology in the sedentary areas where upgrades were absent. The factors responsible for the adoption of the new forms and elements were subsequently identified. The research proceeded by examining literature, physically identifying and mapping out the upgraded sections of the city core, carrying out spot assessment of buildings with observation schedules, conducting interviews with state government officials and individuals in the study area and administering a close-ended questionnaire to generate requisite data and information on the objectives of the research. The data obtained from the research which were both quantitative and qualitative were subjected to analyses. It was discovered that the current threshold of the indigenous building morphology in the areas devoid of upgrading is still the post-vernacular style with strong inclinations towards the forms and elements of the early vernacular building pattern. The new buildings in the upgraded sections of the study area are mainly commercial and mixed-use buildings with a blend of postmodern forms and elements within the basic vernacular style. The new forms and elements in the aftermath of the regenerative efforts in the area are wider windows, long span aluminium roof finishes, deeper eaves and generally larger buildings. The research concluded that urban upgrades have stimulated far reaching changes in the indigenous building pattern around the areas where they have been carried out. These changes which were not pre-empted by the government while executing urban upgrades are reducing the patrimonial stock of the indigenous buildings and resulting to a loss of heritage values in the built environment. The study exposed the need for urban upgrade programmes to envisage and accommodate farther reaching changes in the indigenous building morphology when executed in historic city centres
