Green urban planning has attracted growing attention over the past ten to twenty years. The main theme of this chapter is: how, and to what extent, has the green structure been integrated into the urban planning of Oslo, and what significance has been ascribed to 'greenness' in key planning documents from the 1900s through to the present day? The term 'green structure' in line with what is usual in key Norwegian documents on the subject such as guidelines from the authorities, reports from the Norwegian parliament. The development of park areas in the eastern parts of the city, along the Akerselva River, became part of a new planning focus, where green spaces for the general public in and around the residential areas were given priority over prestigious park developments in city centre. As planning director, H. Hals contributes significantly to the modernization of Oslo, including the addition of green spaces in the master plan, as part of the planning philosophy.