Sledge's Safe House consists of a sprawling and dimly lit interior, apparently built into the rock as a mostly subterranean structure. It bears many hallmarks of a bunker, indicating that it may have operated as a command bunker, or secure storage facility, supporting the mining operations in the area. Sledge's men have since infested the site and repurposed for use as a bandit stronghold.
One wall within the safe house has a set of four QR codes on a wall, just before you start hearing about the claptrap. The bottom code reads www.gearboxsoftware.com, the usual use of such bar codes. The upper right code reads "CL4P-TP was here!"