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>
    <alllinks galcontinue="Castellum|21" />
  </query-continue>
  <query>
    <pages>
      <page pageid="4" ns="0" title="Hoofdpagina" />
      <page pageid="7" ns="0" title="Ulpia Noviomagus Batavorum, Nijmegen" />
      <page pageid="20" ns="0" title="Gebiedskaart NOVIOMAGUS Nijmegen" />
      <page pageid="29" ns="0" title="Gebiedskaart LUGDUNUM Katwijk aan Zee" />
      <page pageid="33" ns="0" title="Gebiedskaart FORUM HADRIANI Voorburg" />
      <page pageid="48" ns="4" title="Limes-wiki:In het nieuws" />
      <page pageid="136" ns="0" title="Botsing van culturen" />
      <page pageid="523" ns="0" title="Pax Romana" />
      <page pageid="632" ns="0" title="HKKO: De Hooge Woerd" />
    </pages>
  </query>
</api>