The Sonsbeek Pavilion – designed as a temporary space to house a series of smaller sculptures for 1966 Sonsbeek exhibition – was open for a single summer only. It then took on a life of its own as a design in the form of a handful of photos, a plan drawing, a photo of a model, and a set of sketches. As a result, this key work in Van Eyck’s modest built oeuvre acquired the status of ‘paper architecture’ – known and discussed on account of the theoretical concept it embodies, but no longer experienced as a real spatial structure.

For that reason alone, it’s good that the pavilion has been rebuilt, since it allows us to test again in reality the theory of the ‘paper plan’ featured in so many architecture reviews. It’s as if the pavilion has descended from the realm of theory and concept and has again set foot on solid ground. Now it is something we can touch and understand. What’s more, it even has its former function: to provide space for a number of small sculptures.

The reality test was certainly surprising. To me, the real thing was better than the impression I’d had of the design over the years. The theory goes that the pavilion is an example of Van Eyck’s search for labyrinthine clarity, for an alternative to the far-too-easy configurative structuralism, for the reconciliation of opposites (in this case, parallel walls and round forms), for the building as a city – in short, for the entire Van Eyck shebang. It’s all true, and it even works, but you forget it straight away once you see and experience the pavilion.

First of all it’s clear that the pavilion does what it’s supposed to do: provide space for sculptures. For despite how emphatic it is as an autonomous design, the sculptures are what grab your attention as you walk through the pavilion. Or rather, your attention switches back and forth between what is a complex, labyrinthine architectural space and the sculptures standing in that space. It is precisely that ‘in-between space’, between architecture and the art it houses that one can explain and theorise about to one’s hearts content, but it can only be experienced in reality.

An important aspect of the design, and of Van Eyck’s total body of work, is reciprocity. It’s often referred to as the twin phenomenon and can be defined as the reciprocal, simultaneous reconciliation of opposites. The relationship between parallels and circles, between constriction and expansion, in the design of the Sonsbeek Pavilion shows what Van Eyck meant with this concept of reciprocity. It is difficult to grasp but becomes crystal clear after a visit. The contrast between the inner world of overlapping circles with diagonal sightlines and the rigidly ordered parallel walls is understandable from every spot in the pavilion. A visit to the structure makes clear once again that ‘paper architecture’ can never be a substitute for built reality, let alone that the idea in its purely ‘paper’ form constitutes a superior sort of architecture as people sometimes argue. With a good design, built reality beats the theory on all counts.

During his introduction Francis Strauven referred to another theme in the work of Van Eyck that can be discovered in the pavilion: the more or less fractal form relation between the part and the whole, the building as city, the city as building. Van Eyck illustrated this somewhat debatable aspect of his discourse with the tree-leaf relation (a tree is like a leaf, and a leaf is like a tree). In response, Christopher Alexander remarked that, no matter what, a leaf is no tree (and a building thus no city). According to Strauven, the parallel walls of the pavilion represent alleys and streets, while the circles are city plazas. Yes, you could read that into the plan, although it is a rather simple form relation. The truth is that the 'city feeling' is scarcely present. Though that city-building reciprocity may have been important to Van Eyck himself in his design concept, the pavilion itself is mainly what it is: a complex, cleverly elaborated architectural space and not a city. His Orphanage, by contrast, is a much more convincing example of a 'city'-building.

The reconstruction (directed by Hannie van Eyck and Abel Blom) is faithful. Only the roof has changed. It was originally covered with a simple structure of steel beams and translucent fabric. (Or was it plastic? The visitors from back then weren’t sure any more). The rebuilt pavilion has a similar steel structure (in which an ingenious drainage system has been integrated), but the roof is covered with completely transparent semicircular plastic cylinders. As a result, the space below is decidedly different to the original. The pavilion is now much more open on top than the original space, which was more enclosed. The old roof did allow light to penetrate the interior, but it was expressly non-transparent. The reason for the change is not clear.

The use of extremely cheap concrete elements, simple steel beams and fabric gave the original pavilion a pleasantly informal, almost Arte Povera character. The new roof has a somewhat high-tech feel to it and is emphatically present as a result. What’s more, the concrete tiles are still very clean and look too tidy. Luckily they’ll probably weather quickly in such wooded surroundings. No wonder it was the roof that the visitors and colleagues from back then grumbled about more than anything else. After all, there has to be something to complain about during a celebration. But it didn’t dampen the high spirits and enjoyment in this small rediscovered masterwork.

The Rietveld Pavilion had already turned the museum’s sculpture garden into a regular destination on many an architecture tour. Another attraction has now been added to the itinerary.