Zellige tiles are one of Morocco's most valued and recognizable art forms. But this type of tile isn't cheap, especially compared to other popular machine-made tiles. A square foot of zellige tiles can cost $50. Compare that to ceramic subway tiles, which might only cost $0.15 per square foot. The craft of making zellige tiles is centuries old, but it may be dying as young artisans lose interest in the trade. So why are zellige tiles so expensive? And how is Morocco preserving this valuable art?