Coherence of city form and consistency throughout the city centre are important objectives, and great differences in density disturb this unity. The city centre is not a project, but a continuous process. Thus, it benefits from fine grain developments on the principle of a rich built environment being generated through small contributions by numbers of people over time. A concept is proposed that densification has positive outcomes up to a point at which negative effects begin to occur. Density is readily measured, but the question remains where the balance point is for each city. There is also a notion that negative impacts may occur before a stipulated density is realised. Support is needed to develop a virtual city model for all cities, and funding to advance city information modelling for all aspects of sustainability, to encourage optimum levels of densification to be achieved.