Dethier Architectures of Koblenz, Germany won entry for an open-sided gallery as part of a large-scale horticultural festival. The event site was the ehrenbreitstein fortress, a UNESCO world heritage site that overlooks two rivers below.
The building itself is triangular in shape and cantilevers 15 meters out over the valley below. Warm materials and lightweight construction allow the structure to be relatively free standing in nature.
Both the location and angular shape of the Belvedere reflect the nearby fortress foundations and surrounding gardens while blending into the landscape.
The Bundesgartenschau is a large-scale event, and the city of Koblenz needed an infrastructure capable of meeting the challenge. Part of the preparations involved an international competition for the construction of a belvedere, to be built on the site of the Ehrenbreitstein Fortress, which overlooks the confluence of the Moselle and Rhine rivers. The fortress is an outstanding site that became a popular tourist attraction after the First World War, and it has been placed on UNESCO’s World Heritage List.
The Belvedere is in the shape of a hollow triangle positioned on the plateau overlooking Koblenz. A walkway, accessible to visitors with limited mobility, leads from a gallery – a potential exhibition space – to the roof, along with a pathway offering, by turns, views of the park, the city, and the Belvedere itself. The cantilever symbolizes the project: it extends more than 15 meters out over the valley and rises 10 meters above the ground. The choice of materials (native wood species for the structure and walkway, and Cor-Ten steel for the structural elements), meant that the entire construction could be pre-fabricated. The marriage of architectural research, and engineering to ensure stability, have resulted in a lightweight structure with dynamic visitor circulation. The lateral trusses create a mosaic of the surrounding countryside and allow the structure to be relatively free-standing.
With its formal, high-tech design, the Belvedere offers a vision of modernity. The integration of a maximum number of contextual characteristics reflects a willingness to foreground the perception of nature. A correct solution needed to be found so that, in a completely unostentatious manner, the structure could stand as a symbol of Koblenz. Moreover, it was essential to enable each visitor to have a meaningful, subtle encounter with the surroundings. 
The choice of Douglas fir and other materials – and above all an examination of the site’s morphology – allowed this “architectural object” to encompass these concerns. As a largescale construction, the structure can be seen from afar, but its grace and horizontality allow it to blend harmoniously into the valley’s landscape. The surrounding park’s features were also determining factors. In response to the organizers’ request that the project respect the historic nature of the site, the belvedere’s location and angular design were chosen to reflect the fortress’s foundations and the garden pathways, which appear to cantilever out over the valley and the Deutsches Eck.
Project Info:
Architects: Dethier Architectures
Location: 56068 Koblenz, Germany
Architect in Charge: Dethier Architectures
Structural Engineering: Ney & Partners
General Contractor: Mohr Ingenieurholzbau GmbH
Area: 675.0 sqm
Project Year: 2011
Project Name: Belvedere for Koblenz Bundesgartenschau
All Images Courtesy Of Dethier Architectures
By: Alice T. Hellyar