Site Size: 5,225 square feet Project Size: 1,104.4 square feet Program: The clients—a family with two children—asked Austrian firm Marte.Marte Architects to build a minimal alpine vacation house. Solution: The architects designed Mountain Cabin, a poured-in-place concrete four-story structure in the Laternser Valley in western Austria, which sits on a sloping ravine near a convent near the edge of a forest. Reminiscent of a medieval fortress, the house is a small monolithic tower with a square floor plan. Irregularly placed windows puncture the thick, rough walls and spaces appear to be carved from a solid block, especially at the midsection