This book contains the invited lectures presented at the 3th International Symposium on Geotechnical Engineering for the Preservation of Monuments and Historic Sites (IS NAPOLI 2022, Naples, Italy, 22-24 June 2022). It collects the opening address, the third Kerisel Lecture, four keynote lectures and eleven panel lectures, and provides a broad impression of 1. the current state of knowledge and 2. the techniques used worldwide for the preservation of built heritage. When confronted with structures relevant to local and global history, there is only one way to select the best possible conservation solution: the multidisciplinary approach. Therefore, the invited speakers have been selected with different pertinent skills, to represent this complexity from the points of view of geotechnical engineers, structural engineers, architects and conservation experts. The book will be useful to researchers, practitioners, administrations and all those working or interested in the preservation of built heritage.