The thing is not easy and it is almost always necessary to introduce artificial intelligence techniques, such as neural networks or genetic algorithms, whose \"training\" is obtained by simulating the behavior of the structure in the presence of various damages using computational mechanics. Finally, also for the purpose of planning maintenance and evaluating the compatibility of its economic cost, there is the prevision of the remaining life. In summary, SHM includes: (1) detection, (2) localization, (3) quantification and (4) prevision of remaining life. Being clear that the SHM is multidisciplinary, the guest editors proposed to the scientific community to contribute to this Special Issue of _Applied Sciences_ international journal, discussing the innovations relating to the methods and materials that allow to evaluate the health status of a structure or infrastructure, limited to those of civil use. Several topics are related to the Special Issue, such as intrinsically diagnostic materials [2], or composites [3], modeling of structures using finite element methods [4], and recently SHM connected with IoT [5]. Problems of surveying structures, methods useful for remote monitoring of infrastructures, in particular, bridges [6] or works of historical-monumental importance were also addressed [7]. Recently, the guest editors have also started to evaluate the economic effects of the SHM, in particular on the estimated value of residential buildings [8]. Since SHM is interdisciplinary, several research fields are involved. Among them we can emphasize the following ones:  
1. The Computational Mechanics. In fact, it is important to simulate the intact and damaged structure in order to identify the presence of the damage and evaluate its position and entity. Without it, the cases that an Artificial Intelligence method uses to train oneself to interpret the data coming from the sensors to arrive at the correct definition of the damage, could hardly be populated. Fundamental concepts in Elasticity, Mechanics and Wave Propagation, Signal Processing, Application of the Finite Element Method in SHM, Spectral Finite Element Method, are some of the important aspects for SHM of competence of this discipline [9]. 2. The Theoretical Analysis of Structures, especially the dynamic one. It is necessary to develop static and dynamic analysis methods, adapting well-known theories to be able to simulate the behavior of a structure and to interpret the data coming from the sensors, which measure static quantities (translations and rotations, temperatures, inclinations, etc.) or dynamic ones (accelerations, vibrations, etc.) [10,11]. 3. The New Materials. There are self-diagnostic materials that can become sensors themselves and make it possible to identify the damage. Furthermore, materials capable of self-repairing and materials that allow a structure to change shape or to react to stresses are appearing (i.e., smart, adaptative and intelligent materials). In the near future, these materials will be of great importance in structural monitoring [12]. 4. The Electronics, Sensors, often in connection with the Internet of Things (IoT), in the measurement of mechanical and structural characteristics. It is important to develop new accelerometers, less intrusive and expensive, possibly connected wirelessly. However, also classic sensors such as strain gauges, inclinometers, LVDTs, etc., must be rethought as a function of modern monitoring, hopefully to be carried out remotely and for a large number of structures [13]. 5. The Artificial Intelligence (Neural Networks, Genetic Algorithms, Machine Learning, etc.) that now pervades most of the technological applications and that allows to make the structure as well as smart even cognitive, that is, able to predict future damage, thus significantly helping scheduled maintenance [14]. 6. Finally, Geomatics and surveying techniques in the continuous and discontinuous monitoring of structures.