The aim was to secure, connect and develop the diverse open spaces in our region in the long term. The towns and municipalities of Alfter, Bonn, Bornheim, Niederkassel, Sankt Augustin and Troisdorf have joined forces to achieve this. The project is unique in Germany and was funded by the Federal Ministry of Transport, Building and Urban Development, the state of North Rhine-Westphalia and the European Union as part of Regionale 2010.

The key project was "Bridging the Rhine" - the redesign of the Mondorf Rhine ferry landing stages. The Green C created a link between the Siebengebirge Nature Park and the Rhineland Nature Park across the Rhine. Covering an area of around 37 square meters, the Green C stretches from north to south over 9 kilometers and from west to east over 17.5 kilometers. The open space is made up of large areas of arable land, orchards and horticulture, old cultivated landscapes, nature reserves, rivers and banks, gravel pits, farm tracks, country roads, freeways and power lines.

Nature conservation, preservation of agriculture, development of local recreation areas - there is a lot to do. Above all, the edges of the Green C are to be protected, strengthened and shaped in the long term in order to set sustainable limits to the settlement pressure of the heavily urbanized region and to secure the endangered cultural landscape for the future:

A "park of cultural landscapes" is being created between the cities.

The ideas for this open space project had already existed for many years when the Regionale 2010 offered the opportunity to detail the planning ideas and implement the project in its entirety. Submitted as a project outline in 2003, the Green C became a pilot project of the Regionale in 2005. In 2015, all project components had been implemented. Green C is not completed at the end of the implementation period. There are a variety of planning and content-related questions regarding further development (see Integrated Green Infrastructure Action Concept).