Citadel at Aleppo, Syria

• The symmetry group of the tiling is *442 (p4m).
• All the internal angles of the constituent polygons are a multiple of 45°.
• Contains one regular two-pointed star polygon with vertex angle of 45°.
• Contains two regular octagons.
• There is one non-regular reflective tile.
• The tiling satisfies the two-colour condition.
• The tiling is edge-to-edge.
• As drawn, contains about 141 polygons.

1. Figure 5.6.2 on page 264 of B Grünbaum and G C Shephard. Tilings and Patterns, W H Freeman, 1987. ISBN 071671193. [gands] {Most important work in this area.}
2. Page 37 (Citadel, Aleppo, Syria) of Robert Field. Geometric Patterns from Islamic Art and Architecture, Tarquin Publications, 1998. ISBN 189961822. [field4]
3. Page 43 of David Wade. Pattern in Islamic Art, Studio Vista, 1976. ISBN 028970719. [wade] {Some beautiful coloured patterns, but source not given.}

• Wade photo PIA 043

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