Horde's standard directory structure looks like this:

index.php               Application index script
foo.php                 Application web-accessible scripts
config/                 Application configuration files
docs/                   Application documentation
graphics/               Application graphics
lib/
    Application.php     Main application code library
    base.php            Common script dependencies
    version.php         Application version information
template/
    common-header.inc   Common page header template
    common-footer.inc   Common page footer template
    foo/                Templates for "foo.php"