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="20171128134437" timestamp="2017-11-28T13:44:37Z" ns="0" title="Institucional" />
        <page value="20171129155107" timestamp="2017-11-29T15:51:07Z" ns="0" title="Historia" />
        <page value="20171129155155" timestamp="2017-11-29T15:51:55Z" ns="0" title="Normativa" />
        <page value="20171201131506" timestamp="2017-12-01T13:15:06Z" ns="0" title="Consulta de Inscripción" />
        <page value="20171201160824" timestamp="2017-12-01T16:08:24Z" ns="0" title="Almacenamiento Virtual" />
        <page value="20171201160925" timestamp="2017-12-01T16:09:25Z" ns="0" title="Correo electrónico" />
        <page value="20171201165143" timestamp="2017-12-01T16:51:43Z" ns="0" title="Servicio de Internet" />
        <page value="20171201165244" timestamp="2017-12-01T16:52:44Z" ns="0" title="Atención al usuario" />
        <page value="20171205115118" timestamp="2017-12-05T11:51:18Z" ns="0" title="Registro Permanente" />
        <page value="20171205150440" timestamp="2017-12-05T15:04:40Z" ns="0" title="Licencias" />
      </results>
    </querypage>
  </query>
</api>