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>
    <querypage qpoffset="10" />
  </query-continue>
  <query>
    <querypage name="Ancientpages">
      <results>
        <page value="20110912191147" timestamp="2011-09-12T19:11:47Z" ns="0" title="Stuttgart 21/Stresstest/Nachweis durch Audit?" />
        <page value="20110914071402" timestamp="2011-09-14T07:14:02Z" ns="0" title="Stuttgart 21/Stresstest/Nachweis durch Audit" />
        <page value="20111030082725" timestamp="2011-10-30T08:27:25Z" ns="0" title="Stuttgart 21/Stresstest/Gescheitert" />
        <page value="20111031044225" timestamp="2011-10-31T04:42:25Z" ns="0" title="Stuttgart 21/Stresstest/Regidisp-Simulation" />
        <page value="20111110005819" timestamp="2011-11-10T00:58:19Z" ns="0" title="Linientausch" />
        <page value="20111221113852" timestamp="2011-12-21T11:38:52Z" ns="0" title="Energie" />
        <page value="20111222170634" timestamp="2011-12-22T17:06:34Z" ns="0" title="Infosammlung Erneuerbare Energien" />
        <page value="20120312191549" timestamp="2012-03-12T19:15:49Z" ns="0" title="Stuttgart 21/Stresstest/Kritik der SMA" />
        <page value="20120512144950" timestamp="2012-05-12T14:49:50Z" ns="0" title="Stuttgart 21/Stresstest/Unabhängige Prüfung" />
        <page value="20120515110029" timestamp="2012-05-15T11:00:29Z" ns="0" title="Stuttgart 21/Stresstest/Brandschutz" />
      </results>
    </querypage>
  </query>
</api>