No, the walls are in your heart.
Uncaged is a multiplayer map in Halo: Reach and is very similar to The Cage. This map is not readily available in Forge, it can only be played/edited in Forge or Custom Games by saving the map from his or her temporary history.
Differences from The CageEdit
This map is almost identical to The Cage in that they have only two differences. A man cannon can be found on the lowest level of the central structure and there is a ramp connecting the centre to the walkway by the cliff. It is in exactly the same location as The Cage and has very similar weapon spawns, only the shotgun in The Cage is replaced with a grenade launcher in Uncaged.