Saskia Sassen explores how the digitised, global and dematerialised institutions of the economic sector adopt a specific kind of materiality, one that incorporates both their physical and digital natures. These materialities are at once territorialized and deterritorialized, global yet concentrated in specific places. Sassen asks whether the specific kind of materiality underlying this interface economy carries implications for architecture rather than simply 'building'. She believes that there are three issues at stake here: one relating to the nature of the subeconomy (internally networked, partly digital and orientated towards global markets); the second relating to the point of intersection between a firm's digital and physical spaces; and the third concerning the question of contextuality in architectural practice. Saskia Sassen is Ralph Lewis Professor of Sociology at the University of Chicago and Centennial Visiting Professor at the LSE. She is the author of numerous books including Cities in a World Economy and The Global City.NB: Slight sound and image interference.