A massive monolithic hunk of sculpted concrete with no visible windows sounds like a pretty unpleasant place to live. Wouldn’t it be dark and cold inside" Could such an alienating structure, presenting no public face whatsoever, ever feel welcoming" To architecture firm Double (o) Studio, the inscrutability of this unusual home is part of the point. The rest is the sky.

Inside the house, there’s no shortage of natural light, with various openings and skylights producing glowing shapes on the concrete floors, stairs, and white walls. Mimicking the topography of the slope outside, the home’s interiors can also be said to follow a much more straightforward logic than the strange and irregular exterior. This geometry becomes clear when viewed from above.
The firm adds that “’Casa Trevo’ exerts a peculiar sense of autonomy and monumentality, despite its small size. It is unified by concrete on the outside, subverting the perception of its scale, while serving as canvas for a dialogue between nature and architecture to be projected. It also exudes a solid impression of mass while revealing little of its inside. The house produces its own introverted world facing the sun, with private yet mutable spaces rendered intermittently by Lisbon’s brash light.”

A house like this isn’t for everyone, of course, and it’s fair to ask how well its multi-level layout and unforgiving surfaces will serve its retired owners i...