Have fixed visible URL

Use FRAMESET with only one defined FRAME, the visible URL will always be the FRAMESET page.

<HTML>
<HEAD>
<TITLE>Visible URL is always the same</TITLE>
<FRAMESET rows="100%,*">
<FRAME src="pagea.html">
</FRAMESET>
</HEAD>
</HTML>

<HTML>
<HEAD>
<TITLE>PAGE A</TITLE>
</HEAD>

<BODY>
pagea
<p><a  href="pageb.html">pageb</a>
</BODY>
</HTML>

<HTML>
<HEAD>
<TITLE>PAGE B</TITLE>
</HEAD>

<BODY>
pageb
<p><a  href="pagea.html">pagea</a>
</BODY>
</HTML>

Try it here