Abstract: A system and a method of long-term condition monitoring of structures are based on use of autonomous sensing modules, centers for storing and processing data and software for data analysis. An autonomous sensing module contains a set of sensors for measurements of parameters related to the condition of a monitored structure, a non-volatile memory, a wireless data transfer unit, a controller, a clock circuit, a battery, an energy harvesting device and a power management unit. The autonomous sensing module provides a very long-term (40 years or more) functionality and reliability due to both use of at least near hermetic packages for the controller, the non-volatile memory, the battery, the clock circuit and the power management unit and choosing the duration of periods when the sensing module works in active mode in such a way that the average energy consumed by the autonomous sensing module is fully compensated by the average energy harvested by the energy harvesting device.