templates/categories.html

{% extends "base.html" %}
{% block title %}Categories{% endblock %}

{% block content %}
<article>
  <div id="article_text">
    <ul>
      {% for category, articles in categories %}
      <li><a href="{{ SITEURL }}/{{ category.url }}">{{ category }}</a></li>
      {% endfor %}
    </ul>
  </div>
</article>
{% endblock %}