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="20160524030816" timestamp="2016-05-24T03:08:16Z" ns="0" title="Main Page" />
        <page value="20170327172957" timestamp="2017-03-27T17:29:57Z" ns="0" title="Serielle Kommunikation (MS-Windows)" />
        <page value="20170327172957" timestamp="2017-03-27T17:29:57Z" ns="0" title="Ordner und Dateien (Qt)" />
        <page value="20170327172957" timestamp="2017-03-27T17:29:57Z" ns="0" title="Standard Template Library STL (C++)" />
        <page value="20170327172957" timestamp="2017-03-27T17:29:57Z" ns="0" title="Ein- und Ausgabe (C++)" />
        <page value="20170327172957" timestamp="2017-03-27T17:29:57Z" ns="0" title="Grafik (Qt)" />
        <page value="20170327172957" timestamp="2017-03-27T17:29:57Z" ns="0" title="Verschiedenes (Qt)" />
        <page value="20170327172957" timestamp="2017-03-27T17:29:57Z" ns="0" title="Qt (C++)" />
        <page value="20170327172957" timestamp="2017-03-27T17:29:57Z" ns="0" title="Taktgeber und Zeitmessung (Qt)" />
        <page value="20170327172957" timestamp="2017-03-27T17:29:57Z" ns="0" title="Fallen (C++)" />
      </results>
    </querypage>
  </query>
</api>