Step inside the Piñeiro House and you're 15 stories above Buenos Aires—but you'd never guess it. This architects of Adamo-Faiden crafted a 215-square-foot pavilion for a couple living in the building. The sun-filled room seamlessly transitions, via sliding glass doors, to a smaller canvas-shaded outdoor terrace. The entire addition is lined with hedges that provide shade and privacy. The architects say these rooftop "spaces are privileged places…When we conquer them, we manage to lay ourselves on the edge of the town in contact with the atmosphere." In other words, they make for a sweet place to hang out.