In the context of the need to accommodate increasing urban populations and densities, many emerging building types incorporate increasingly large and complex shared circulation spaces. These ‘semi-public realms’ can be found in both perimeter block and 'megastructure' types and present potential benefits but also potential problematic consequences for the combined private, semi-public and public realms. Key issues include: ambiguity of form, boundaries, use, control, and imagability. Some of the factors at the root of these issues include lack of connectivity, excessive connectivity, excessive spatial depth, lack of hierarchy and spatial differentiation in relation to depth. As the latter points suggest, a key concept that can help in understanding these issues - and contribute towards designs that avoid them - is depth. Within the field of built form studies and urban morphology, the idea of depth encompasses a number of different specific conceptions. Three of the most relevant are: configurational depth (Hillier and Hanson 1984), territorial depth (Habraken 1998) and structural depth (Conzen 1969, Caniggia and Maffei 2001, Arthur 2011, Kropf 2017). The aim of this paper is to show that these three forms of depth are not mutually exclusive but have specific complementary relationships that can be used together to undertake a coherent, 'multiple depth' analysis of built form. Using examples of contemporary buildings types with extensive semi-public realms, the paper goes on to show how such an analysis can aid in both urban design practice and urban design education.