The purpose of this plan was to introduce the imaginary environment concept to modem environment design which was drawn by comparison of historic and cultural landscape. An area of $19,056m^2$ in I1-ja mountain water reservoir, located in 94 Dun-Chon-Dong, Gangdong-Gu, Seoul was selected for this planning. The concepts of Barrier-Free Design and Universal Design were introduced in order to accept the demands of various social classes. Based on the results of natural and cultural environment, Animism, Heaven, Earth and Man Theory and Yin-Yang and the Five Elements Theory these concepts were introduced for the philosophical background. Concept planning, topic selection, space planning and axis establishment were conducted during the framework step of the plan. Circulation planning, planting planning, facility and pavement planning, and light planning were conducted during the initial planning step. Lastly, detailed designing was performed for the major spaces. In addition, the imaginary environment concept was applied, ranging from the structural aspect of the space to designing factors of the facility in order to achieve placeness and practicality. In conclusion, this may be the first case design applying the imaginary environment concept to the environmental design with natural environment factors such as animals, plants, terrains and climate, and cultural such as cities, places, time, thoughts and symbols which are all factors to be considered in the existing environment design.