Located in Sardinia close to Lula, the region of the Sos Enattos mine is understudies to host the third generation of gravitational wave interferometer: Einstein Telescope (ET). The Sar-Grav laboratory, a seed of ET, will host underground experiments, cryogenic payloads, low frequency and cryogenic sensor development that need low seismic and anthropogenic noise. Indeed, the Sos Enattos mine already hosts seismometer and magnetometer nets, located both on the surface and underground, that prove the quietness of the site. On the surface area, the Sar-Grav laboratory is characterized by a hangar of 900 square meters equipped with rooms for the experiments, an optical laboratory, and a control room. An area of 250 square meters and small experimental areas are planned to be located underground where stations at different depths already host the sensors net.