Incidents such as building and bridge collapse are on rise in many parts of the world without little apparent warning. Due to the increase number of incidents it has become of increasingly paramount importance to develop methods detecting the degradation or damage that result in these events. Thus, buildings and critical infrastructure could be monitored, much like a patient in a hospital, for signs of degradation or impending disability or collapse. The sensors are very important to know the state of the health of the structures and technologies are like human brains to analyze the abnormal situation. This chapter will provide a review of different available sensors and technologies to be used for monitoring the health of structures.