Abstract: The measuring system for monitoring buildings, terrain sections or the like consists of a beam waveguide bending sensor which has a multimode beam waveguide (GI) and is disposed in the shape of a loop. Several arc-shaped sensor sections (S) are disposed between support plates, which are movable in respect to the sensor sections and and fixedly connected with areas of the building or terrain sections. A light source and light receiver with an evaluation device for light subduing values are connected to the beam waveguide bending sensor. The beam waveguide bending sensor is disposed in the form of several loops. The beam waveguide bending sensor consists of gradient-index-multimode beam waveguide sections (GI) and step-index-multimode beam waveguide sections (SI) connected therewith, wherein the sensor sections (S) are formed by the gradient-index-multimode beam waveguide (GI).