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This image comes out of page 226 of "Visions of Symmetry - Work of M.C. Escher" by Doris Schattschneider. The book was published by W. H. Freeman in 1990.

This pattern is described as "The Cairo Tiling" by F.S. Hill Jr. because it is seen in street paving frequently in the city of Cairo. The pattern is also used in Japan for concrete paving. This whole drawing is based on two square units each 100x100 pixels. One unit has an X shape in orange, the other unit has an X shape in green and rotated 90 degrees. The amazing thing about this graphics is that only intergers are used and the smallest resolution is 5 pixel. This is a fun geometry to understand. Part of the clue is show in the Escher book on page 227. The pentagons have equal sides but unequal angles. Eli Maor discussed this geometry in the book "To Infinity and Beyond" (Princeton University Press). The secret to this tessellation is that 4 of the pentagons form a hexagon.