Intra-city natural structures have always had a key role in creating sustainable urban greenspaces. Adapting to natural features and relating the intra-city greenspaces to such natural structures as river-valleys, hillsides, lakes and forests, guarantee the endurance, sustainability and longevity of the natural quality of city. This paper looks at intra-city natural structures which have undergone wholesale changes and been ruined, and considers the lives of these invaluable natural structures which have been endangered due to gross human interference and pressure, regardless of physical and biological features. River-valleys in Tehran have always had a significant role in offering valuable bio-environmental services to the city. From the time of Qadjar era, villages enjoying favorable climate were built outside the city, and the villa of the governors and affluent people were built near hillsides across river-valleys because of the abundance of running water, cool weather in the summer and natural plant life. Little by little green corridors of Shemiranat were built near river-valleys, which formed the axes of the development of the city at the time Pahlavi dynasty. From then, the development of the city towards hillsides, regardless of these natural structures, increased and the destruction of these urban natural spaces have posed serious problems nowadays. Familiarity with these natural structures, their preservation and organization, and making the optimum use of them seem to be a very critical issue. Taking an ecological approach in this paper, is an attempt to look at the intra-city river-valleys. To do so, the data collected from a natural river-valley is used as evidence to back up any claims made in this regard.