Listening to the cosmos from underground: that's the project of the Einstein Telescope (ET), an underground detector for gravitational waves that will further expand our knowledge of the universe. It is a large European research infrastructure, with candidate sites including the Sos Enattos mine in Sardinia, Italy, and will act as a driving force for the development of new knowledge and technologies for research, as well as for the growth of the community and the territory that hosts it.