Updated Feb, 22nd 2013
(test grouping directory contains links to the project files as well as Windows and Mac builds)
I used plains to creat the walls, floor and ceiling and applied old looking brick textures to the walls with some weathered looking cement for the ceiling and floor. I found an old looking metal table, a door, some trees and an old wooden box through the asset store. I shrank a Japanese maple from the asset store and scaled a barrel to use as a planter pot to create a banzai, finishing it off by duplicating a rock and scaling it several times to cover the wooden top of the barrel.
Finally, I played around with the lighting by adding a low intensity directional light colored blue to cool off the environment and a low intensity point light bringing a bit of attention to part of the banzai. I tried to figure out a bit about baking a light map, but I'm going to have to work a lot more to understand them.