South end of the eastern building in the Nunnery. Notice the lattice-like stone mosaic that simulates a woven surface on the building's frieze. On the woven pattern sit eight bicephalic snakes which are progressively shorter, forming a trapezoid geometric shape. The corner of the building displays the familiar stack of deity masks. What make this building a tour de force of Puuc architecture, however, are its clean lines, the play of light and shadow created by its double threshold doors, and the pleasing contrast between the ornamented upper frieze and the plain lower wall, framed from below by the regularity of its base of junquillos (small stone cylinders).