Micro-Electro-Mechanical Systems (MEMS) enables the use of embedded micro mechanical devices, such as sensors, valves, gears, mirrors or actuators, into a substrate semiconductor. They can be easily integrated into normal chips, providing useful and very compact devices able to measure physical quantities. Thus, MEMS promises to revolutionise the future structural monitoring systems by combining microelectronics and technology of "micro machines", making possible the realization of complete System-On-a-Chip at relatively low cost. This paper presents a MEMS-based monitoring system able to detect and locate damages through an array of sensors and a software able to exploit the differences among the recorded signals. Experimental results indicate that system could estimate incipient damages as well as monitoring their evolution along time. This methodology is well suited to prevent unsafe conditions in masonry structures and could be extended to monitoring concrete and steel structures.