Abstract: As people’s longing for nature-experience is growing, providing access to nature in the city is becoming increasingly relevant both politically and in practice. The idea of and planning for “Urban Wilderness” promises a special kind of nature-experience. Acknowledging how different perceptions create conflict, landscape architects must try to understand which wilderness perceptions exist and what they might imply. Employing three categories, “Unknown Wilderness”, “Specific Wilderness” and “Process Wilderness”, this essay discusses ideas of wilderness that have developed over millennia until today. For the purpose of this essay, the term “colonisation” serves as key to understanding how ideas of wilderness develop. Natural processes include colonisation of space by plants and animals. Processes of people entering and taking ownership of areas include colonising space physically, mentally and spiritually. Naming areas is a special form of mental and symbolic colonisation, for example, when people “discover” wild looking vegetation in the city and calling it “untamed nature”, or “Urban Wilderness”. However, most current and particularly official definitions of wilderness exclude human interference: Once colonised, “True Wilderness” ceases to exist. Scientific studies have contributed much knowledge about natural processes and colonisation but little about people’s ideas of and attitudes towards nature and wilderness. For landscape architects it would be important to learn more about how “designing and constructing with (ideas of) nature” might contribute to providing desirable landscapes. This essay discusses some (of the many) attitudes and thoughts related to discourses, planning and design for and of “Urban Wilderness”.