This publication represents a quest for biodiversity in the city. Declining biodiversity in the countryside has been in the spotlight for years. Healthy soil life is of vital importance. Biodiversity in the city appears to be hidden. How do you design a public space that is anchored in healthy soil? There is a world full of life beneath our feet. Hidden in the soil, up to 100 million species of micro-organisms work together with fungi and plant roots to form networks that ensure a healthy living environment. Without soil, we cannot survive. Yet we treat our living environment inattentively. The growing world population is moving to cities, annexing surrounding areas and literally squeezing the life out of the soil. The urban climate, urbanized environment and urban water balance are detrimental to healthy soil life. The (urban) soil is largely sealed off and this results in extreme flooding, heat and drought exhaustion, soil compaction and habitat fragmentation. The design of the city includes many underground measures. Every change leads to soil exhaustion. This has to change. BiodiverCITY formulates measures and resulting details that will result in healthy soil life.