There is a remarkable tradition that stands for a close relationship between good architecture or good city form, and the precise dimension of their elements. It defends the existence of well-defined rules that link the parts with the whole city, smart rules that were applied from ancient times until present. In this paper I would like to discuss some of these arguments, checking how designers have long sought for measures that assure the good shape of the city, its best performance, hygiene, safety and beauty. Among these rules density has quite recently become one of the most relevant attributes to describe the form and characteristics of a city. Therefore Vertical Cities Asia has proposed a project set on a main parameter, a density of 100.000 people per square kilometre. It is certainly a remarkable high density. But is it too much? And until what extent a given density may determine the urban form? I would like to share with you ten propositions regarding these questions