Escher and the Alhambra

M. C. Escher visited the Alhambra in 1922 and 1936 while he was there he made lots of sketches that were to become a big inspiration for much of his future work. The intricate decorative designs of the Alhambra, based on symmetry featuring interlocking repetitive patterns in the colored tiles or sculpted into the walls and ceilings, triggered his interest in the mathematics of tessellation and rotational symmetry.

Rotational symmetry, is the property a shape has when it looks the same after some rotation by a partial turn. An object's degree of rotational symmetry is the number of distinct orientations in which it looks the exact same for each rotation.