In the undulating forest landscape around Arnhem in the eastern part of the Netherlands, revalidation centre ‘Groot Klimmendaal’ can be found standing as a quiet deer in between trees. From a small footprint, the building gradually fans out towards the top and cantilevers out over the surrounding terrain. Despite its size, the brown-golden anodised aluminium facade allows the nearly 14.000sqm building to blend in with its natural surroundings. Full height glazing along the central space connecting the various different internal elements of the building ensures an almost seamless continuity between interior and exterior. The meandering facade in the restaurant results in a building in between trees and invites the forest inside the building. The surrounding nature has a strong visual and tangible presence everywhere in the building; it allows the user to revalidate whilst walking.‘Groot Klimmendaal’ is part of a masterplan also designed by Koen van Velsen. The masterplan envisages the area, largely built upon by one and two-storey buildings, to be gradually transformed into a public park landscapeThe arrangement of the programme is clear. Below are offices, above are the clinical area’s and on the roof a Ronald McDonald House with its own identity. The double-height ground floor at entrance level facilitates the special elements of the programme such as a sports facility, fitness, swimming pool, restaurant and theatre. Not only patients but also family members and members of the local community (schools, theatre groups etc) use these facilities on a regular basis. As a result, both patient and building are placed at the centre of the community.The care concept is based on the idea that a positive and stimulating environment increases the well-being of patients and has a beneficial effect on their revalidation process. The design ambition was not to create a centre with the appearance of a health building but a building as a part of its surroundings and the community. Revalidation centre ‘Groot Klimmendaal’ radiates self-confidence and self-control. The welcoming and open environment offers a natural habitat for care but at the same time allows plenty of opportunity for other activities. The building is the result of an intensive collaboration between architect Koen van Velsen and the users of the building. For example, a shallow timber staircase runs the full internal height of the building and is typical for the new integral way of working. It facilitates a direct route between the different floors but also enables a variety of alternative routes roaming the building and thus forms an invitation to undertake physical exercise.A combination of large and small voids and light wells ensure a spatial connection between different levels and allow natural daylight deep in the heart of the 30metres wide building. Interplay of striking but subtle colours and direct and indirect (artificial) lighting enlivens the interior. The use of energy is amongst others reduced by the compact design of the building and the design of the mechanical and electrical installations. Most notably the thermal storage (heat and cold storage) contributes to the reduction of energy consumption. The choice of selecting sustainable building materials and materials requiring little maintenance for floor finishes, ceilings and facade cladding result in a building which can be easily maintained and with a long lifespan. The building has been custom made for its users but the design offers at the same time opportunities for different ways of using the building and the inevitable transformations of different departments within the client’s organization.Revalidation centre “Groot Klimmendaal’ is a coming together of both complexity and simplicity with attention for physical, practical and social details. Transparency, continuity, layering, diversity, the play of light and shadow and the experience of nature are all ingredients of this stimulating environment.