Stefan Eberstadt was living in a tiny New York apartment when the idea for the Rucksack Haus first hit him: “I imagined a space [outside] of the window—a walk-in space to extend my room.”

Rucksack Haus is a portable extension that hangs from steel cables fastened to its host building. Eberstadt, an artist now based in Munich, Germany, worked with engineer Thomas Beck to build the house last fall. “Hanging it was the biggest challenge,” Eberstadt says, “but we did it in under a day.” He claims the parasitic addition can be suspended from most buildings as long as they are structurally sound. The cables take the weight of the house—just under 1.5 tons—plus the weight of up to ten people, and anchor it to the roof or far side of the host building.

“So many people live in these dark, cave-like apartments with only one window,” says Eberstadt. “I wanted the Rucksack Haus to be as open as possible.” Although it is a mere 97 square feet, the high ceiling gives it a tremendous feeling of space.

Expounding further on the motivation behind the Rucksack Haus, Eberstadt states that he wants to “irritate” our perception of city streets. He explains that in many of Europe’s more formal cities, nothing disrupts the clean building façades, but elsewhere in the world life literally spills into the street. “I want to get a vision started,” says Eberstadt, “to make people think about where they live. Can I imagine hundreds of Rucksack Hauses hanging everywhere? Yes, why not?”