This terrifying structure is part of an irrigation system used in the Valais region of Switzerland since the 15th century. Some bisses are still in use, while others are designated as historic landmarks. It's a way to get water from the Alpine mountaintops to the dry valley farms that need it.
Despite being surrounded by some of Switzerland's wettest mountains, the sun-scorched, glacier-carved region receives just 500mm of rainfall a year, presenting a unique engineering challenge for irrigation. Cue gravity-defying bisses, designed to divert glacial meltwater from mountain streams to parched pastures and vineyards at lower elevations. To this day, 200 of them totalling 1,800km in length supply water to 80% of the Valais' irrigated land.
Measuring between 0.5m to 2m in breadth, the most primitive of Valais bisses were hewn out of rock. Others, like the 500-year-old Bisse des Sarrasins in the district of Sierre in central Valais, were hollowed from tree trunks. But the true marvels of bisse engineering were the "hanging channels", designed to guide water from far-off glaciers around gorges and overhangs in the region's wildest corners.
Now imagine the labor and the danger involved in building these in the 15th century. Read about the Swiss bisses at BBC Travel. -via Damn Interesting
(Image credit: Rilaak)