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>
    <querypage name="Ancientpages">
      <results>
        <page value="20131011172341" timestamp="2013-10-11T17:23:41Z" ns="0" title="I²C API" />
        <page value="20131011173931" timestamp="2013-10-11T17:39:31Z" ns="0" title="Application Ideas" />
        <page value="20131011190132" timestamp="2013-10-11T19:01:32Z" ns="0" title="Main Page" />
        <page value="20131014143358" timestamp="2013-10-14T14:33:58Z" ns="0" title="User Manual:Index" />
        <page value="20131014143935" timestamp="2013-10-14T14:39:35Z" ns="0" title="Frequently Asked Questions" />
        <page value="20131015175337" timestamp="2013-10-15T17:53:37Z" ns="0" title="Downloads" />
        <page value="20131024033917" timestamp="2013-10-24T03:39:17Z" ns="0" title="Microcontroller And Electronics" />
        <page value="20131026014625" timestamp="2013-10-26T01:46:25Z" ns="0" title="REST API" />
      </results>
    </querypage>
  </query>
</api>