This book comprises the proceedings of the third TMM_CH International Conference on "Transdisciplinary Multispectral Modelling and Cooperation for the Preservation of Cultural Heritage." This book showcases the latest advancements in non-destructive testing and structural techniques across a wide range of applications within the realm of cultural heritage. The conference, held at the esteemed Eugenides Foundation in Athens, Greece, brought together scientists, engineers, architects, archeologists, conservators, geologists, art historians, and other stakeholders. Thirteen sessions and panel discussions featuring 142 esteemed panelists provided a platform for the exchange of ideas. With a significant online presence and approximately 50,000 online viewers, the conference had a profound impact on a global scale. This book serves as a valuable resource, presenting recent scientific breakthroughs, non-destructive techniques, and technologies that contribute to the holistic preservation of our world's cultural heritage.