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>
    <allimages gaicontinue="14_Fisch04_Klaus_Venus_Bildband_2010.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="154" ns="6" title="File:0060.jpg" />
      <page pageid="112" ns="6" title="File:03 Altstadt Sonnenbrücke 2 - Klaus Venus 2009.jpg" />
      <page pageid="121" ns="6" title="File:07 Dom innen - Karl Hofman.jpg" />
      <page pageid="164" ns="6" title="File:1-BBM-21368.jpg" />
      <page pageid="165" ns="6" title="File:1-BBM-21371.jpg" />
      <page pageid="134" ns="6" title="File:1.jpg" />
      <page pageid="142" ns="6" title="File:11.jpg" />
      <page pageid="118" ns="6" title="File:11 Kaiserdom aus dem Ballon - Klaus Landry 2007.jpg" />
      <page pageid="120" ns="6" title="File:13 Kaiserdom mit Dachlandschaft - Klaus Venus 2009.jpg" />
      <page pageid="137" ns="6" title="File:14.jpg" />
    </pages>
  </query>
</api>