Nearly every classic zellij panel radiates from a khatam, the eight-pointed star made by laying one square over another at forty-five degrees. The khatam is the seed of the composition. Around it the cutter sets rings of strapwork, interlacing bands that widen outward ring by ring, and the geometry is so ordered that the radiation could in principle continue without limit; the panel ends where the wall ends, not where the pattern does.
From the same grammar the masters of Fez developed rosettes of far higher order, stars of dozens of points whose spokes fan out into lattices of astonishing fineness, the accepted proofs of a master's rank. The tradition's monuments stand on both shores of the strait that joins Morocco to al-Andalus. In Fez, the madrasas of the Marinid sultans wear dados of zellij beneath carved stucco and cedar; in Granada, the lower walls of the Alhambra carry cut-tile panels whose interlocking figures so fascinated the twentieth century that M. C. Escher's tessellations began from sketches he made there.
The craft is not a museum piece. Restoration of the royal cities, mosques and public fountains of Morocco keeps whole workshops employed, and new commissions travel worldwide. What the visitor sees as ornament is therefore also an unbroken chain of transmission: the same shapes, cut the same way, assembled face down in the same order, for some seven hundred years.