<a href="https://en.wikipedia.org/wiki/ambigram" class="extiw" title="en:ambigram">Ambigram</a> <a href="https://en.wikipedia.org/wiki/Tessellation" class="extiw" title="en:Tessellation">tessellation</a> <b><a href="https://en.wikipedia.org/wiki/M._C._Escher" class="extiw" title="en:M. C. Escher">Escher</a></b>, showing the name "Escher" right side up and upside down using <a href="https://en.wikipedia.org/wiki/negative_space" class="extiw" title="en:negative space">negative space</a>. 180° rotational symmetry. <a href="https://en.wikipedia.org/wiki/M._C._Escher" class="extiw" title="en:M. C. Escher">M. C. Escher</a>'s work features mathematical objects and operations including impossible objects, explorations of infinity, reflection, symmetry, perspective, and tessellations.
<a href="//commons.wikimedia.org/wiki/User:Basile_Morin" title="User:Basile Morin">Basile Morin</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>