The Serpentine Gallery has commissioned Olafur Eliasson and architect Kjetil Thorsen to design its Pavilion in 2007. Based on the principle of a winding ramp, the Pavilion explores the idea of vertical circulation within a single space. Our collaboration on the Serpentine Pavilion 2007 is defined by our mutual focus on the experience of space and on temporality as a constitutive element of spaces, private or public. We both work within a field of spatial experimentation that renders conceptual differences between art and architecture superfluous. The publication comprises extensive visual material documenting the development and realisation of the pavilion; two essays by Doreen Massey, Professor of Geography at The Open University (UK), and Andreas Ruby, architecture critic; a conversation between Olafur Eliasson, Kjetil Thorsen, Hans Ulrich Obrist and Julia Peyton-Jones (Co-directors, Serpentine Gallery).