Built into a hillside gazing down upon the bustling city of Stuttgart, Germany, a ‘mountain crystal’ glitters in the sun as an artificial extension of its natural surroundings. Smooth, modern and monolithic, ‘House 36’ by Matthias Bauer Associates looks for a balance between the solidity of stone and the fragility of crystal, mirroring them in concrete and glass. The effect is that of a rough-cut gem newly hacked from a surrounding matrix of igneous rocks, all the more beautiful for its unexpected contrasts.

Concrete architecture has a reputation for feeling cold and impersonal, especially in the sort of modern architectural designs that don’t take great pains to soften it with lots of warm, organic wood and vivid color treatments. ‘House 36′ is more concrete than not, and the hard surfaces that immediately surround its exterior lack lush landscaping that could help liven it up. All the same, it manages to avoid the harsh Brutalist connotations usually associated with the material. That’s largely thanks to the architects’ nuanced composition and eye toward sustainability, as they attempt to combine “a stone cavern with a glass house.” While the jointless walls are solid concrete, large expanses of glazing connect the interiors to the stunning vistas outside, with only the mostly windowless street-facing facade of the home giving the appearance of an impenetrable fortress.

Working with a modest plot, the a...