Except for a giant window thrust into one side, this man-made intervention, a 270-square-foot one-room dwelling, could be just another one of the mossy weathered boulders dotting Costa da Morte. Instead, the guesthouse blurs boundaries between architecture and landscape. "It's a piece of nature built with our own hands," architect and engineer García-Abril says. "A space within a stone that blends with the surroundings. A contemplative space, a little poem."