A long-standing urban design principle is that successful places exhibit vitality, being vibrant and diverse. This vitality depends on levels of economic and social success that sustain over time urban diversity including cafes, restaurants, delicatessens, bakeries, cinemas and galleries, grocery stores, pubs and clubs of varying sizes and types to suit individuals of varying taste, preference and socio-economic status. Accordingly, a successful public realm includes a complex 'transaction base' of activities. Since vitality occurs in physical, primarily human-made built forms and spaces, the qualities of physically permanent urban places influence vitality. However, the built form may eventually become inappropriate for its original purpose, the use redundant, or changes to demand may occur. Many buildings and spaces, specifically, are therefore refurbished or reused, but time, cost, inability, or environmental constraints associated with changes may impede physical change and therefore the ongoing maintenance and enhancement of places' vitality. Importantly, some physical structures facilitate adaptability better than others overcoming a decline of activity or the need for expensive adaptation or outright demolition and redevelopment. This research examines the suggestion that greater levels of place adaptability facilitates higher levels of ongoing vitality, due to the ability for structures to be used for a range of purposes over time, without the need for changes to physical form, particularly in the move to higher densities. The paper outlines a method for measuring vitality and building adaptability in parallel and reports the results of empirical research of key locations in Melbourne's Central Business District (CBD). It is argued using empirical data that adaptability, when translated to actual adaption, facilitates sustained vitality.