Designed by Torsten Klocke of 10 Liter Design, the Rohbau birdhouse is made from concrete with a wooden door to protect its inhabitants from "the wind, the weather, and potential enemies."

Above: The Rohbau Birdhouse measures about 10 inches at its highest point; €89 at Das Rote Paket.

Above: Birdhouses in production.

Above: The 35mm hole is suited for great tits, tree sparrows, redstarts, common flycatchers, and pied flycatchers.

N.B.: This post is an update; the original story ran on June 16, 2009.