near the Qasr El Nil Bridge and the El Behoos Metro station; other versions of the tiling are visible elsewhere in the city. Some authors including Martin Gardner have written that this pattern is used more widely in Islamic architecture, and although this claim appears to have been based on a misunderstanding, patterns resembling the Cairo tiling are visible on the 17th-century Tomb of I'timād-ud-Daulah in India, and the Cairo tiling itself has been found on a 17th-century Mughal jali. One of the earliest publications on the Cairo tiling as a decorative pattern occurs in a book on textile design from 1906. Inventor H. C. Moore filed a US patent on tiles forming this pattern in 1908. At roughly the same time, Villeroy & Boch created a line of ceramic floor tiles in the Cairo tiling pattern, used in the foyer of the Laeiszhalle in Hamburg, Germany. The Cairo tiling has been used as a decorative pattern in many recent architectural designs; for instance, the city center of Hørsholm, Denmark, is paved with this pattern, and the Centar Zamet, a sports hall in Croatia, uses it both for its exterior walls and its paving tiles. In crystallography, this tiling has been studied at least since 1911. It has been proposed as the structure for layered hydrate crystals, certain compounds of bismuth and iron, and penta-graphene, a hypothetical compound of pure carbon. In the penta-graphene structure, the edges of the tiling incident to degree-four vertices form single bonds, while the remaining edges form double bonds. In its hydrogenated form, penta-graphane, all bonds are single bonds and the carbon atoms at the degree-three vertices of the structure have a fourth bond connecting them to hydrogen atoms. The Cairo tiling has been described as one of M. C. Escher's "favorite geometric patterns". He used it as the basis for his drawing Shells and Starfish (1941), in the bees-on-flowers segment of his Metamorphosis III (1967–1968), and in several other drawings from 1967–1968. An image of this tessellation has also been used as the cover art for the 1974 first edition of H. S. M. Coxeter's book Regular Complex Polytopes. References External links Isohedral tilings Pentagonal tilings Semiregular tilings Culture in Cairo