Courtines Diest - de ontwikkeling van een citadel

The roofscape atop the courtines is a rooftop park of unprecedented scale, beauty and surprise. Where between mysteriously incised pathways, through walls and gates you enter the enclosed world of the citadel, here, through narrow passages and stairs you suddenly find yourself on top of it. You rarely come across a rooftop park like this, with metres of soil and, with it, beautifully developed extraordinary vegetation.

The landscape and geomorphology define the appearance of the Citadel's historic location: a fortress high atop the mountain with unobstructed views over the surrounding area with a tightly planted forest that was supposed to keep the enemy at bay. The landscape relics of the past are today's gold. There is a mature forest with mature oaks, beeches and elms. The roofscape with special ostrich grass vegetation on acid soil make it a unique landscape next to the city centre. Due to change over time, the area has become largely inaccessible and has lost its original functions. The aim of our design proposal is to protect the valuable (historical) landscape, make it accessible and experienceable. We will restore some crucial internal and external connections and add some new paths, bridges, routes and programmes.

The visitor enters the Courtines through the original gate that will be restored to its former glory. The curious visitor discovers the small court of Bastion 1 immediately after entering. This intimate anteroom contains the entrance to the rooftop park, an outdoor terrace of the café. The space is defined by its proximity to the historic walls, the museum gates, the existing paving of concrete slabs and cobblestones. Some contemporary, smaller architectural interventions create a subtle metamorphosis that guides the visitor's exploration: a large window, a sliding gate and a slightly receding, elegant lift tower. The walking route for lift users and walkers meet at altitude where the walk across the rooftop park begins, with different views, past some follies, along possible boardwalks and mowed paths.

Along the inner facades of the Courtines, we provide new egress windows with gently sloping green edges that rise towards the square. They form a slightly sunken residential zone around the square. We choose a generous size that relates well to the scale of Paradeplein and the monumental buildings. In addition, the gentle slope ensures good light and residential quality. The egress windows introduce the human scale, shelter and coolness while preserving the existing trees.

Since its construction in the 19th century, the citadel has been in use and thus in constant evolution. Frequent alterations and decay have left traces in the facade. Window openings have been altered, we see frost damage, root penetration above the natural stone frame and water damage inside. The aesthetics of evolution and of decay have become part of the building, in all its strength and all its beauty. We respond to this with a soft restoration - restoring to an original state is not a fair design stance here. Our restoration strategy aims to stop the decay and is based on the preservation, conservation and reuse of the existing material as much as possible.

The art academy currently appears to be housed in an almost ideal way in the existing Logementsgebouw. We propose to retain the Logementsgebouw and renovate it with simple means, in connection with the usability of the existing structure and the design team's responsibility with regard to circularity and responsible handling of available resources. Against the south façade of the building, we provide a wide, vegetable pergola. This creates a natural sun shade, and gives the spaces a layered and pleasant green view.

An ambitious architectural competition with disillusioning ending

The client: the city of Diest with several advisors, also the jury. The assignment: to develop a vision for the redevelopment and conservation of a monumental fort and the development of a part of the building. A task with extreme technical challenges such as moisture, daylight, flexible and sustainable use, and preserving a valuable biotope on top of the roof. Our answer: an integral proposal for preserving the current up to 5m high earth package on the roof and detailed design principles for the interior with its beautiful brick vaults.

The reason for the disqualification of our design proposal? Our research showed that there was insufficient space in the project section to be elaborated for the requested programme unless one were to build on or next to the monument. This seemed undesirable to us. However, there turned out to be an existing building from the 1960s with sufficient quality and the capacity to literally and figuratively illuminate the monument. The problem: although the building is part of the fort, it appears on drawings just next to the project section to be worked out and also on an outdated demolition list. We proposed to retain the building and use it as the fort's technical and spatial ‘outboard motor’, with smart installations and enough suitable space for the part of the requested programme that did not fit in the monument.

With this simple, contemporary solution, we wanted to resist the city's demolition plans, and it simply seemed functional, sustainable and cheap.

However wonderful the Belgian architectural climate sometimes seems: as everywhere, procedures are fragile and depend on knowledgeable, ambitious clients and their advisers. In Diest, we had timely requested the addition of external jurors. When independent judging was refused, we really should have refrained from participating.

What does the question for a vision mean if certain answers cause disqualification and designers are not allowed to speak freely? To what extent is it of our time to reject a more sustainable solution (preservation rather than demolition and new construction), while elsewhere the professional community fights for a ‘demolition ban’? And how do we view the responsibility of public building owners who disregard critical advice from competent design teams for purely procedural reasons?

Can this example be more than a painful lesson? Or can it strengthen our plea for a substantive, fair competition culture with imagination and vision?