Concept and History

Cologne’s urban planning situation up to the beginning of the 1920s was shaped by the fortress conditions of the city. The outer fortress area enclosed the left and right bank of the Rhine on a length of 40 km, 800 – 1,000 m width, with a total area of 4,000 hectares. According to the provisions of the Treaty of Versailles, the fortifications had to be destroyed after 1919. It is the merit of Federal Chancellor Konrad Adenauer (from 1917 – 1933 Cologne’s Lord Mayor), who had the idea for the development of a closed green system, that the area was not cultivated after the abolition of the fortress property, but was formed as a green area. The basic concept came from Fritz Schumacher, Director of Construction of the City of Hamburg, who was brought to Cologne by Adenauer for 3 years (1920 – 1923). Schumacher planned a radial green system that surrounded the city and was to be connected to the city centre by green corridors in order to create a ventilation system that would “flood the stone structure of people with air”. The site was to be divided into different zones: an allotment garden zone adjoined the city’s buildings, thus forming a flowing transition. Beyond the military ring road follows a zone of playgrounds and sports facilities, which merges into a free green area. This zone is to be afforested “according to assets and needs, so that the district can form a hygienic fortress as a protective wall against the approaching lignite industry”. (Quote: Schumacher)

The conversion of the fortress belt into a green belt was essentially carried out in two construction phases as part of emergency work with the unemployed between 1919 and 1929:

First City Forest extension (1919 – 1923)

Planner: Fritz Encke (1903 – 1926 Director of Horticulture in Cologne).

Concept: designed as a forest park, in line with the concept of the adjoining city forest. The monotonous terrain was made more varied by extensive ground movements. The height differences were to be increased by planting mainly on the heights and arrangement of the meadows in hollows and valleys.

Second Green Belt (1927 – 1929)

Planner: Theodor Nußbaum, park architect and town planning officer (1926 – 1945), closely following Schumacher’s basic concept.

Concept: “Social green space programme

“In addition to extensive forest areas, large public and sunbathing lawns are planned, as well as those for sport and play, air and light baths, gardening and forest schools, allotment gardens, cycle and riding paths, ponds for biking and ice sports, as well as places for the construction of cottages and rural taverns in connection with meadows and pastures.” (quote: Nußbaum)

As there were no natural forests in the area of the outer green belt, a large contiguous forest area was to be created from species-rich mixed forests, mainly deciduous wood.

“For the care and management of the forest the peculiarity of the forest area as a recreation area is decisive. Since clear-cutting cannot be considered here, future thinning will be carried out in Plentermanagement. This type of silviculture, applied by the large forestry industry in many areas, conveys the most valuable forest picture through the mixture of different age groups.” (Quote: Nußbaum)

Heritage preservation aspects

The heritage register of the city of Cologne lists the entire area of the Outer Green Belt as a green area worthy of preservation. In the 1920s, the idea of creating coherent green systems prevailed in Germany. In almost all German cities, concepts for a complete urban green system were drawn up. In the vast majority of cases, however, it remained only theoretical considerations. The unique thing about the Cologne green system is that it was possible to shape an entire urban green system and in some areas also to design it. Not only the pure area of the green belt, but also its inner structure and the interlocking with the city are of importance for the preservation of historical monuments: for example the gradation from the building development, over an allotment garden zone, a zone of sports and play facilities to the forest and meadow zone. The fact that the green belt was laid out on the former fortress site and that some of the design of the fortifications could be integrated is also of importance in terms of heritage conservation.

Green Belt extension (1955 – 1965)

While forests were sacrificed for urban development purposes in other cities after the Second World War, Cologne took the opposite path in its green policy. In the mid-1950s, the city began a major reforestation programme. Also this time the Cologne green system with the Outer Green Belt was the most important connecting point. The sole motive was creating recreational forests and protective forests. The rapid economic development of the post-war period and the associated environmental pollution made it urgently necessary to create forest areas to improve the environmental quality in the city. In the period from 1956 to 1965 alone, 1,000 hectares of agricultural land were afforested to expand the Outer Green Belt and create the Forest Botanical Garden. Forests were established next to industrial plants and along motorways to protect against visual disturbance and air pollution, and water protection forests were established. The orientation towards the urban green system led to reforestations being largely systematic and starting where forests made it possible to expand existing green spaces. Today, with a forest area of 4,000 ha, Cologne is one of the largest municipal forest owners in North Rhine-Westphalia.

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