Option 1 mod_rewrite / ISAPI filter to rewrite
For mod_rewrite on Apache, it is as simple as adding a .htaccess file to the root directory of your website with the following content...
The following rule will direct all URIs in this format:
http://yoursite.com/Content/Page/
to
http://yoursite.com/Page.php
IE the last bit of the URI gets transformed into a PHP file of the same name.
RewriteEngine on
RewriteRule ^Content/([^/\.]+)/?$ $1.php [L,NC,QSA]
Option 2 directory structure
This is where you have a folder structure to represent your website and each folder has an index.php file. For example,
http://yoursite.com/Contact-Us/index.php
In this example, visiting
http://yoursite.com/Contact-Us/
gives you the extensionless URI that you are after as the index.php page is shown by default.
I only mention this as it is a solution for a situation where you on shared Windows hosting and cannot add an ISAPI filter.