Help creating a route for sub-folder holding controllers

In my CI application, all of the administrative actions are in controllers within the /controllers/admin/ folder....

[root@server application]# tree controllers/
controllers/
|-- Account.php
|-- Api.php
|-- Assets.php
|-- Dashboard.php
|-- Group.php
|-- Help.php
|-- Main.php
|-- Page.php
|-- Partition.php
|-- REST
| |-- Account.php
| |-- Admin.php
| |-- Analytics.php
| |-- App.php
| |-- Assets.php
| |-- Key.php
| |-- Page.php
| `-- Partition.php
|-- admin
| |-- Accounts.php
| |-- Backups.php
| |-- Groups.php
| |-- Home.php
| |-- Logs.php
| |-- Pages.php
| |-- Partitions.php
| |-- Plugins.php
| |-- Recyclebin.php
| |-- Roles.php
| |-- Settings.php
| `-- Support.php
`-- index.html

The question I had was how can I have it so when they go to application.com/admin/, it shows a resource in a specified controller?

I tried adding the following to application/config/routes.php, but it didn't work:

PHP Code:

$route['admin'] = '/admin/home'; 


I tried it with/without the slash after admin, as well as with/without slashes before/after the admin/home didn't work.

Obviously creating an Admin.php inside the application/controllers/ directory would work for the /admin/ index, but make all the controllers inside the application/controllers/admin/ inaccessible.

Thanks!