The center of Lima is a heritage of great historical and artistic value, currently in an advanced state of decay, threatened by speculative pressures and not protected by appropriate laws and regulations. This book, published with the support of World Monuments Fund, presents the approach developed in the joint research carried out in the year 2009-2011 by the Faculty of Architecture of Sapienza University of Rome, Italy and FAUA - Facultad de Arquitectura, Urbanismo y Artes - of National University of Engineering of Lima, Peru: the research focused on identifying and evaluating the endangered heritage preliminary to the rehabilitation process. Part one introduces the historic city since its foundation by the Spaniards, also identifying tracks and remains dating before the Spanish period, well worthy of protection for future generations, through the use of hitherto unpublished maps. The second part presents the conservation issues facing the historic center of Lima and, more generally, the theoretical and methodological tenets for the restoration of historic urban areas, followed by an overview of endangered heritage and significant rehabilitation works carried out in the city in the last ninety years. The third part analyzes the typical local construction techniques and some of the related methods of preservation, finally centering on the rehabilitation works of the Casa de las Columnas, supported by the World Monuments Fund.