Ammann-Beenker Tiling
An aperiodic tiling with
8-fold rotational symmetry using just two tile types:
Squares and
45-degree Rhombuses
Discovered independently by Robert Ammann and F.P.M. Beenker in the 1970s-80s, this tiling is related to octagonal quasicrystals.
Ammann bars are straight lines that cross all tile boundaries, revealing the hidden long-range order.