DAVID LEATHERBARROW is Professor of Architecture at the University of Pennsylvania, where he also serves as Interim-Chairman of the Department of Architecture and Associate Dean of the School of Design.  He teaches architectural design, as well as the history and theory of architecture, gardens, and cities.  His recent books include: Architecture Oriented Otherwise; Topographical Stories: studies in landscape and architecture; Surface Architecture, in collaboration with Mohsen Mostafavi; and Uncommon Ground: architecture, technology and topography.  Before that were: The Roots of Architectural Invention: site, enclosure and materials, and On Weathering: the life of buildings in time, again with Mostafavi.  His research has focused on selected topics in the history and theory of architecture, also landscape architecture, and, most recently, the impact of contemporary technology on architecture.