San Pedro cliff (Figure 1) is a dihedral 65.5 m high, which has progressed to place itself at 23.8 m from the Alhambra wall-palace that is a heritage of the Humankind. Active normal faults surrounding the cliff have created an extension tectonic regime that loosens the ground and activates the slab falls. One of the faces of the dihedral is a major fault. The cliff’s factor of safety subject to the 1000 years return period earthquake is 0.73. The preservation solution proposed is a post-tensioned high elastic limit wire mesh and autochthonous vegetation. With this reinforcement, the factor of safety under that earthquake raises to a value around one. A computer simulation has permitted to analyse the environmental impact.