Mud can hold up a seven-storey home

You could be sleeping sixty feet in the air on a bed made of nothing but wet dirt and straw. In the city of Shibam, Yemen, builders used sun-dried mud bricks to stack homes seven storeys high. These aren't tiny huts or temporary shelters. They're genuine skyscrapers made from the same stuff that sticks to your boots after a rainstorm.

It works because mud is surprisingly heavy and stubborn when you treat it right. To build a tower like this, you mix clay, sand, and water into a thick sludge, pour it into molds, and let the sun bake it hard. These blocks are called adobe. If you get the recipe wrong, the bricks will crack as they dry, but a perfect mix creates a wall so dense it can support the weight of six other floors pressing down on it.

Living inside one of these walls feels different because the dirt is actually a battery. Thick earthen walls have high thermal mass, which means they soak up the sun's heat all day long without letting it pass through to the inside. The rooms stay cool while the sun beats down. Then, when the desert air turns freezing at night, the walls finally give up that stored warmth, heating the house like a slow-release radiator.

But there's a catch to living in a house made of dust. The entire seven-storey structure is technically trying to dissolve. Moisture is the enemy, and if the roof leaks or the base of the wall stays damp, the clay can soften and lose its grip. The only reason these towers haven't slumped back into the earth after hundreds of years is that people constantly patch them with fresh coats of mud.

It's a strange trade-off for a skyscraper. You get a home that breathes with the temperature and carries its own weight, but the moment you stop grooming the walls, the house begins to melt. You aren't just living in a building. You're living in a pile of geology that's waiting for a reason to become a puddle.