Nacadia Therapy Garden is constructed on a one hectare parcel in the Hørsholm Arboretum, which is located 30km north of Copenhagen. The Hørsholm Arboretum covers almost 40 hectares and contains the largest collection of plants and shrubs in Scandinavia, with over 2,000 different species. It is characterized as a healing forest garden, which could be described as a garden with a natural forest appearance, based on the presence of trees, shrubs and perennial plants. In terms of the design, Nacadia Garden is characterized as a behavioural setting-a place where the physical environment and human behaviour are indissolubly connected. The Nacadia project has four objectives: a) provide treatment for patients with stress-related illness; b) obtain evidence-based knowledge about the effect of healing garden design and Nature-Based Therapy (NBT) for this patient group; c) develop and offer education within the field of healing garden design and NBT in general; d) serve as a knowledge and demonstration centre for the public. Based on this, Nacadia is designed according to 10 overall criteria, which are based on research evidence as well as documented experiences from other therapy garden projects: 1. Spatial structure. The garden must be perceived as a whole. It consists of a large room with several smaller rooms. 2. Living building material. The walls of the rooms are formed by shrubs or green fences, the floors are made of grass or wood and the roofs are formed by treetops or pergolas with flowering climbers. 3. Easy to interpret. The clients must be able to interpret what the garden can offer them, and what they may do. 4. Security. The garden provides a sense of total security. The green walls block outsiders’ visual or physical access. 5. Levels of Safety. During the treatment process, the clients must be exposed to less safe and more demanding areas. The location of the garden within the Arboretum offers an extra semi-safe zone, which the clients can visit as they become better. 6. Strength of Mind . The clients’ experience of nature and the level of demands they are able to handle depend on their emotional and cognitive resources. 7. Mental and physical accessibility. Mental accessibility is about attracting the clients into the garden. At the same time, it is important that the visible attractions are also physically accessible. By using different natural paving materials and varied terrain, the clients’ body awareness and fitness are improved. 8. Flexibility and Participation. As a result of the evidence-based design process, the garden will be regularly evaluated and redesigned over the years. In one room of the garden called ‘the free forest’ the clients can be creative and influence the garden’s design. 9. Perceived Sensory Dimensions of Nature. Research shows that people classify natural environments in terms of eight specific characteristics called Perceived Sensory Dimensions. Some of those are preferred over others by people suffering from stress. 10. Opportunities for nature-based activities. It is fundamental that the garden offers opportunities for meaningful activities all year round. Some activities are practical in nature, while others are symbolic. The design of Nacadia and the NBT concept was developed from 2007-2009 by an interdisciplinary group at the University of Copenhagen, lead by landscape architect Ulrika Stigsdotter. The group includes landscape architects, medical doctors, psychologists, and therapists with expertise in the field of nature-based therapy and stress treatment.