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>
    <allfileusages gafcontinue="Brabo1.jpg|107" />
  </query-continue>
  <query>
    <pages>
      <page pageid="263" ns="0" title="Case Studies: Barcelona Europe South Container Terminal, Spain" />
      <page pageid="308" ns="0" title="Case Studies: Liefkenshoekspoorverbinding Liefkenshoek Rail Link" />
      <page pageid="320" ns="0" title="Case Studies: Belgrade By-pass Project Section A: Batajnica-Dobanovci, Serbia" />
      <page pageid="351" ns="0" title="Case Studies: The Blanka Tunnel Complex, Czech Republic" />
      <page pageid="372" ns="0" title="Case Studies: Berlin-Brandenburg Airport, Germany" />
    </pages>
  </query>
</api>