Interaction is a key concept for architect Hans van Beek, in 1976 together with Sjoerd Schamhart and his colleagues Cees Nieuwenkamp and Ernst Verheij founder of architectural firm Atelier Pro. Interaction with the earth, the elements, the earthlings and their comings and goings, but especially with the surroundings and with the employees of Atelier PRO. The book offers a chronological overview of Hans van Beek's most important developments and projects, before and during Atelier PRO. The structure of the book is also based on interaction. Author Marcel Teunissen allows clients and leading architecture critics of the past and present to have their say, but primarily Hans van Beek himself provides context and depth to the projects. Through interludes, he takes the reader behind the scenes of the offices Sj. Schamhart, PRO and ultimately Atelier PRO. He tells the stories that cannot be read from the places and buildings, but which were decisive in their realization. Cross-references show what else the book is about from a different angle. There are connections between numerous buildings, which are not always immediately visible in the chronological overview. Again, these often involve crucial decisions, but at the design level. The overview is marked by the first and last major project: the pioneering, experimental housing complex Couperusduin in The Hague (1971-1976) and the Meander Medical Center in Amersfoort (2005-2013), an international milestone in healthcare architecture. In between lies a rich body of work that was created with great enthusiasm. That oeuvre moves between small and large, remodeling and new construction, transformations and expansions, urban renewal and urban regeneration, building both in historic environments and in undescribed places.