Nowadays the question arises if public urban spaces such as parks, gardens, allotments or fallow areas in the modern city of tomorrow will increase or disappear. Taking into consideration the expansive growing of the European Cities there will be rising demands of recreational space and green areas, so-called "urban nature". Statements like the Agenda 21 and Europe 2000+ on the one hand plead for more nature and open spaces in urban agglomerations, on the other hand a decreasing expansion of the urban areas into their peripheries is to be noticed. Taking up such statements this paper deals with the following questions: What does city development mean for urban nature and open spaces in European cities of today and tomorrow? Is there a need to prefer the model of the compact city to the model of the expansive one which allows more place for open spaces? Which kind of "urban nature" is able to fulfil the requirements of the inhabitants and needs to be preserved?