The THEMIS building is designed to preserve image quality. The rounded shapes of the structure minimize turbulence. Its orientation, aligned with prevailing winds, is optimized to favor morning observations, which are the most favorable. The white-painted aluminum cladding reduces heat absorption. The telescope is supported by an inner concrete tower, independent of the main building, to prevent the transmission of vibrations. The telescope is positioned 22.5 meters above the ground, above the turbulence zone caused by the Sun heating the Earth's surface.