Buildings were once materialized drawings, but now, increasingly, they are materialized digital information - designed and documented on computer-aided design systems, fabricated with digitally controlled machinery, and assembled on site with the assistance of digital positioning and placement equipment. Within the framework of digitally mediated design and construction we can precisely quantify the design content and the construction content of a project, and go on to define complexity as the ratio of added design content to added construction content. This paper develops the definitions of design content, construction content, and complexity, and explores the formal, functional, and economic consequences of varying the levels of complexity of projects. It argues that the emerging architecture of the digital era is characterized by high levels of complexity, and that this enables more sensitive and inflected response to the exigencies of site, program, and expressive intention than was generally possible within the framework of industrial modernism.