In Rails, how to have an /admin section, and then controllers within the admin section?

I want to have a /admin section in my application, and have routes within this /admin section like:

www.example.com/admin/ (only certain users have acess to this section)

then have controllers in this section like:

/admin/users/{add, new, etc}

What are my options for something like this? (using rails 3)