From my old webpage:
Areal photo of Dupont Circle in Washington, DC reveals an (approximate) rare 10-fold symmetry. There are many circles in Washington (according to Wikkipedia there are 33), but no other has the full 10-fold symmetry of Dupont circle.
Penrose tilings, discovered circa 1976 by Roger Penrose. This most highly "symmetric" Penrose tiling is called the "Cartwheel" by John H. Conway.
The basic plan for the city, including the layout of Dupont Circle, is due to Pierre l’Enfant (small insert), circa 1791. Notice the diagonal "state" streets.
Penrose tiling decorated with the Ammann bars, discovered by amateur mathematician Robert Ammann (http://tilings.math.uni-bielefeld.de/people/r_ammann). Note how much the bars resemble "state" streets in Washington. This image can be made to more closely resemble the city plan if it is skewed to make two of the directions perpendicular.
Place Charles de Gaulle in Paris with 12-fold symmetry(!), but with no underlying grid.
Penrose tiling mural at GWU Department of Mathematics
