A quick way to embed literal HTML inside an HTML document is with an xmp tag. I would have put an actual example here, but apparently PerlMonks doesn't like the xmp tag. Here's how you would use it:

<xmp>
HTML list example:
<ul>
  <li>Thing One</li>
  <li>Thing Two</li>
</ul>
</xmp>
[download]

Of course, if the literal HTML contains an XMP tag, you've got problems. Encoding the angle brackets and ampersands is the most robust solution.