Marines with Alpha Company, 1st Battalion, 5th Marine Regiment, practice proper techniques to clear a stairway during an Urban Operations exercise at Marine Corps Base Camp Pendleton, Calif., Jan. 9, 2014. Each building is designed differently to offer an unpredictable layout that Marines would normally experience in UO. The rooms are filled with distracting elements including holes in the walls, open ceilings and multiple doorways.
photo courtesy of: Lance Cpl. Christopher J. Moore, USMC