Stone staircases in the Khumbu region Nepal Himalayas can be quite a workout physically and mentally. Physically because of the rarefied atmosphere (0.4bar) and mentally because often they are sticking out of the side of the mountain with very long drops down into the valley below. They can be built on a semi-vertical rock wall. Holes are bored in the rock, timbers wedged into the holes then flat rocks piled on the protruding timbers. Other places there may be a narrow ledge where large slabs of rock partially overhang the ledge to increase its width.