Three abandoned ruins in Miragaia street, in Porto, are brought to the project: a street facade as a wall; a contiguous building that offers its height; a third ruin on the site that is kept as scenery for a new garden. A movable wall made of Pladur makes it possible for the house to change itself to accommodate four students, while a central core organizes space and infrastructures. The two facades reveal their different character – the city's typical facade to the street and a more abstract one to the interior garden. The fifth facade is also designed with a composition of skylights and solar panels. The end result is a synthesis between traditional and contemporary materials in an ecological design, bringing together the place's identity with new principles of sustainable building – aiming to create a building as natural in the place as a cat in the sun on the stones of a ruin.