Walkability, one of the planning and design topics with a rising importance in Turkey and the world, has been recognized as an urban strategy to conserve and regenerate the historic city centres, to create healthy societies and to generate sustainable and liveable cities. In Turkey, it has been seen as a means of increasing the accessibility of people with disabilities to the urban space in the early-2000s. With the onset of the Healthy Nutrition and Active Life Program of Turkey, walkability has been recognized as a way of combatting obesity and promoting healthy life since 2013. Despite these promising advances, it is still questionable how far Turkish cities have been planned and designed in consideration of walkability. This research, focusing on this question, aims to develop a micro-scale assessment model for examining the walkability capacity of urban space. After investigating the notion of walkability as a component of liveability and quality of life, it describes the measures of the micro-scale 'walkability' assessment model and explains in depth the research methodology. Using the historic city centre of Mersin as a pilot study area, it examines the walkability capacity of Ataturk and Uray Streets in detail. In the final section, it discusses the major planning and design strategies that can improve not only walkability capacity of the historic city centre, but also its liveability and quality of life. Additionally, with reference to a rule-based planning and design approach, it underlines the contributions of the model to the current planning practice, and makes a debate on how the model can be used and developed in the future not only for assessing the walkability capacity of urban space, but also for modelling and investigating the alternative urban scenarios to improve liveability and walkability of cities.