Following in the footsteps of British researchers in the late 70 '(Dragon Project), for about six months we have researched the presence of the emission of ultrasounds from the megalithic structures in Visoko Valley. For our study we used two types of devices capable of capturing with remarkable sensitivity the presence of ultrasounds: a compander (a device that can instantly transform ultrasounds radiation into audible sound) and highly sensitive professional recorders and microphones able to record ultrasounds in order to analyze their characteristics in professional studio. These two different types of methods of research have still achieved the same results because we have confirmed the presence of ultrasounds emitted from the apex of the Pyramid of the Sun, the Pyramid of the Moon, the Tumulus of Vratnica and within Ravne’s Labyrinth.. The latter in particular was an ideal environment for this type of study for its quietness, so that we could also record an infrasonic activity. We also used different types of equipments and microphones to exclude introduction of spurious frequencies by their own devices, but we can conclude that in these structures exist an emission of ultrasounds with special features not found in the surrounding hills, or nearby. We started, therefore, an analysis about electromagnetic activity in the same locations and the results so far appear very similar and overlapping, but we should be studied further this aspect too before obtaining definitive results.