You didn't say what server you were using, but you need to point
passenger to your *public* directory, not RAILS_ROOT as described
here:
Phusion Passenger users guide, Apache version
The Apache VirtualHost section they use as an example is:
With thanks to Hongli Lai over on the Phusion Passenger Google Group, I
got this sorted out. And for completeness and to help others this is
what I did.
I set up a new directory under /var/www:
/var/www/myapp
and created a symlink from there to my app's public folder:
When you say "RailsBaseURI /something", then Phusion Passenger will
look for a filesystem entry "$DOCUMENT_ROOT/something", and this
*must* be a symlink to the 'public' directory of your Rails app.