Stress characterization is critical for any deep engineering project including deep geothermal reservoir development and deep mining projects. For the former stress level influences the reservoir stimulation design and for the latter it guides underground infrastructure design including pillar width, extraction rate for both, stress levels drive rock mass rupture and associated induced seismicity. Result from the Soultz-sous-Froets (France) geothermal project,that highlights the importance of stress heterogeneities and their relation with structures, will be presented. The implication of stress heterogeneities for rock and rock mass failure will be will be discussed, highlighting implications for the design of deep mines.