Urban designers are not used to taking the subsurface into a holistic perspective on spatial development. Nevertheless, the subsurface accommodates numerous functions crucial to urban life, such as infrastructure, carry capacity, heat, water, etc.. Moreover, it also carries the natural system crucial for urban quality and health. In the light of the current climate change, energy transition and the financial crisis these issues are more important for different reasons. The subsurface stores water, plays a role in cooling the city, provides geothermal warmth as renewable energy, and smart use of the subsurface can save considerable money. Besides, urban renewal (brownfield development) is the preferred option over taking new land (greenfield development). Brownfields do not have an unexplored soil system, it is already used in many ways. Therefore ‘Urban design with the subsurface’ should be considered a new frontier in urban planning and design. The neglect of the subsurface in spatial planning is due to the fact that responsibilities, tools and knowledge of subsurface engineering and urban planning and design are not integrated, they work on the same locations but divided into sectors. The urban designer is usually dealing with the opportunities for socio-economic benefits whereas the subsoil engineer deals with the technical challenges. Both on a practical level of building the city, as well as at policy level, ‘subsurface’ and ‘surface’ are separate realms. The aim of this report is to discuss this segregation in three countries that are active in integrating subsurface in urban development: Sweden, Netherlands and Flanders (Belgium). The main research questions are: What characterises these planning systems? How is the subsurface framed in these countries? A comparison is performed as the first step in learning and proposing better ways of integrating subsurface in urban planning and design, and vice versa.