I definitely wouldn't call a 40-foot wide lot minuscule. But I guess when it's located on the side of a mountain in Zell am See, Austria; you have a required 13-foot setback on both sides; and your architect is one of the world's leading practitioners, it starts to feel a bit smaller. This is the recently completed Austrian House, designed by Rem Koolhaas:

I'm always drawn to houses like these because they demand creativity. You can't just repeat what was done on that other 40-foot wide lot, because then you might conclude that the lot is unbuildable. And it's not. You just have to solve the puzzle. Then you've unlocked something that that many, or perhaps most, thought wasn't possible. And that's truly exciting to me.

For more on the Austrian House, check out Architectural Digest.

Photography by Pernille Loof and Thomas Loof