the present invention relates to a method of instrumenting an already erected concrete or rock structure in order to determine the state of deformation of that structure . a cylindrical inclusion made of concrete having substantially the same mechanical properties as the concrete or the rock of the structure is inserted into a hole drilled into the concrete or rock . sensors capable of detecting deformations are embedded in the concrete of the inclusion . the empty space between the inclusion and the hole is tightly filled with a grout whereby any deformation of the concrete or rock structure also deforms the inclusion and is therefore detected by the sensors embedded therein . the invention also extends to the inclusion and the so instrumented concrete or rock structure .