Anton Skryl’, ELSA lab junior researcher, and Dr. B. Jackson of the University of Michigan carried out an experiment on visualizing the internal structure of the fresco “Three men with spears” at the Centre for Research and Restoration of the French Museums at the Louvre in Paris using terahertz radiation.It is expected that drawings dating back to the epoch of the Rome Empire are hidden under the fresco. The fresco was sounded by terahertz radiation in the reflecting mode by the Picometrix T-Ray 4000 spectrometer. The obtained data are currently analyzed.