title: How to include PHP file in Wordpress that is outside the Wordpress Environment
body: <p>I am using a custom CMS for a website that deals with 90% of the site's pages and content.</p>
  
  <p>However, for the news/blog section of the site, I am using Wordpress.</p>
  
  <p>I'm able to include the necessary Wordpress files to pull in posts to the main site, but cannot do the reverse.</p>
  
  <p>I want to be able to call a php file into the header of Wordpress so I have access to the CMS's classes, primarily for navigation.</p>
  
  <p>I've tried a search but can't seem to find an answer.</p>
  
  <p><em>Additional Information:</em></p>
  
  <ul>
  <li>Wordpress is installed in <code>site.com/wordpress</code></li>
  <li>The file I want to include is in <code>site.com/includes</code></li>
  </ul>
  
  <p><strong>Clarification:</strong></p>
  
  <p>I don't want to create a custom template or include Wordpress functionality outside of Wordpress. I want to pull external classes from a CMS, which is a level above Wordpress, <em>into</em> Wordpress so that I can use it throughout the Wordpress installation.</p>