This paper focuses on the work produced in the Architectural Association Diploma Unit 12 and how it incorporates the subjects of infrastructure and architecture through employing ‘indexical systems’. The paper outlines the history of the unit from its inception in 2003, then tutored by Eva Castro and Holger Kehne, to the current tutors, Holger Kehne and Jeff Turko, and the development of the subject matter the studio had been focusing on. The synergies that lay between infrastructure and architecture became the setting in which the unit was to develop concepts and indexical tool sets to address the varied and complex issues. This was done by way of students developing indexical drawings and models digitally through the translation of environmental, structural, organizational, and morphological conditions into gradient fields of varying intensities. The value of these outcomes would be the basis for a subsequent design proposal. The paper then goes on describe the current developments of tools and methods employed in the Unit. First the returning to the use of the diagram, which became central to the design process again. Secondly the engagement with iconography, or rather the development of iconographic images, where the image allows to focus on the actual spatial experience itself in its quality and character. Incorporating visualization into the index in order to avoid the notion of the visual sound bite and to transform it into a means of analysis and evaluation.