Hello;
don't know what is exactly the purpose, maybe you should explain a little more what you are planning to get.
But if you do not want to edit core files, use javascript and iframe in your template HTML files.
Display URL:
<script>
document.write('<center>'+window.location+'</center>')
</script>
Insert HTML file:
<iframe src="http://path_to_your_HTML_file" width="xx" height="xx" scrolling="no" frameborder="0" name="xxxxx" align="center"></iframe>
Don't know if it helps... without editing Core files.