The holographic principle posits a radical way to quantify gravitational physics. It claims that all information of a gravitational theory in a region of space can be encoded by a quantum theory at the boundary of this region. During this colloquium, I will discuss holography from an engineering perspective. We will see how one can engineer—i.e., design and build—gravity through this relationship, using possible quantum theories on the boundary as materials for the undertaking. The concrete advances will be presented for AdS_3/CFT_2: an instance of holography that relates three-dimensional gravity with a negative cosmological constant (AdS_3) to a two-dimensional conformal field theory (CFT_2).