The Dark Knight
Since Wayne Manor was destroyed in Batman Begins, Bruce used the Penthouse as his home and the Warehouse as his base of operations as Batman. It was used to store the Tumbler and the Batsuit. The Warehouse is hidden at one of Wayne Enterprises docks.
The Dark Knight Rises
Selina Kyle helps Bruce break Lucius Fox out of Bane's captivity. He and Bruce then travel to the warehouse for Bruce to gather his Batman equipment including a Batsuit and other tools.