The idea of this new publication by Mark Pimlott originates from a series of lectures given to students of the course 'The Architecture of the Interior' at Delft University of Technology. As the public interior dominates the experience of public environments in our time -- realms currently dominated by infrastructure or commercial interests -- its consideration is essential for all those involved in their making and use. The public interior, as a place in the world for people to be themselves with others, has been designed, and is thus inscribed within culture and its ideas. It seems very important to attend to and discuss these ideas of the public interior -- congruous with those of architecture -- as they have been embodied within it, across time and function. 'The Public Interior as Idea and Project' is a follow up of 'Without and Within: essays on territory and the interior.'