The Rotterdam Roof park is developed in the so called ‘Four Harbours’ Strip: an elongated strip of no-man’s land not far from the city centre of Rotterdam. The assignment is to integrate the development of 85.000m2 of offices, shops and schools with a sea dyke and a public park on top. This project works as a catalyst in the urban transformation of the harbours, and will form a new landmark along the ‘Park lane’ which is one of the most important roads of Rotterdam. The project adds a significant spatial quality to the adjacent neighbourhood Bospolder, which lacks proper green. The roof park is a good example of intensive spatial and multiple ground use. In spite of its many limitations (the altitude, safety issues, narrow shape and climate and constructional requirements) the aim is to create a well accessible and green park.