This masters thesis explores the capacity of Vienna to grow food on rooftop gardens for the nourishment of its inhabitants. Following the global trend of rooftop farming and motivated by the positive effects of urban farming and green roofs on a city, the parameters for urban rooftop farming in Vienna are being analyzed. The objective is to identify which areas are suitable for this type of urban farming, where these areas are located and how much vegetables could be produced on them. This is achieved through literature research and GIS-data analysis. First, existing rooftop farming projects and similar studies that have been carried out for other cities are analyzed. Then, different production methods are considered. The analysis is limited to the production of fresh vegetables.^ ^The consulted production methods are divided into two categories: traditional open-air, soil-based systems that can be installed as green roofs or container gardens and hydroponics in a conditioned greenhouse. After analyzing the specifications of each method, the differences between the two methods with respect to yield, gross/net production area and additional weight are discussed. In order to identify feasible areas, criteria that define the suitability of rooftops are formulated. The focus is set on structural and legal parameters. The study parameters that are considered are: inclination of the roof, quotient area/perimeter, size, location based factors, legal aspects, building use, building structure, building infrastructure and financial aspects. These parameters are first discussed in general and then for specific buildings with the help of five defined typologies as case studies. The results of this analysis are summarized in a practical handbook.^ ^For the connection of the study parameters with the city matrix, existing GIS-data from the city of Vienna is utilized to develop a model of the city with suitable roof areas. The basis for this model is laserscanning and land-use data. The criteria that are considered in the model are roof inclination (less than 5), size (more than 1,000m2 flat gross area), building use and solar potential. The resulting suitable area is about 520 ha gross area. It is discovered that the maximum yield can be achieved with hydroponic greenhouses. On the identified suitable area, a yield of 208,422 t fresh vegetables per year is possible. With this amount, 53.4% of the citys demand for fresh vegetables could be met.