HTML into PHP Variable (HTML outside PHP code)

I think you want heredoc syntax.

For example:

$var = <<<HTML
<html>
   <head>
random crap here
</html>
HTML;

Have you tried "output buffering"?

<?php
 ...
 ob_start();
?>

<html>
   <head>...</head>
   <body>...<?php echo $another_variable ?></body>
</html>

<?php
 $variable = ob_get_clean();
 ...
?>

I'm not really sure about what you are trying to accomplish, but I think something like the heredoc syntax might be useful for you:

<?
$variable = <<< MYSTRING

<html>
   <head>...</head>
   <body>...</body>
</html>

MYSTRING;

However if you are trying to make HTML templates I would highly recommend you to get a real templating engine, like Smarty, Dwoo or Savant.