You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information.
<?xml version="1.0"?>
<api>
  <query-continue>
    <allredirects garcontinue="Gallery" />
  </query-continue>
  <query>
    <pages>
      <page pageid="3718" ns="0" title="Celtic Art Exploration" />
      <page pageid="2077" ns="0" title="Circle Limit Exploration" />
      <page pageid="2017" ns="0" title="Cubic Space Division" />
      <page pageid="1969" ns="0" title="Depth and Perspective" />
      <page pageid="1611" ns="0" title="Development II" />
      <page pageid="2595" ns="0" title="Egyptian Geometry Exploration" />
      <page pageid="3699" ns="0" title="Escher&#039;s Circle Limit Exploration" />
      <page pageid="2124" ns="0" title="Escher&#039;s Hyperbolic Geometry Exploration" />
      <page pageid="2065" ns="0" title="Flatness Exploration" />
      <page pageid="1498" ns="0" title="Fundamental Concepts" />
    </pages>
  </query>
</api>