This monograph discusses the role that ruins play in urban centers in terms of their meaning, testimony, and value, and the opportunities they provide. After an outline of historical and contemporary of ap proaches, with a special analysis of British and Italian approaches, Elisa Pilia puts forward a methodology for the inves­tigation of the strategic values of such ar­tifacts, and ideas for their potential con­tribution to a sustainable requalification of historic urban cores. The protocol is tested on the historical center of Cagliari, a mid­sized port city on the south­ern coast of the island of Sardinia, Italy, where the remains left by aerial bombard­ment during the Second World War are still a dramatic part of the controversial European debate on how to reuse ruins.