It might sound like an exaggeration, but the root bridges of Cherrapunji are indeed alive. Unlike most parts of the world, these bridges are grown, not built.
Known as the wettest place on Earth, Cherrapunji is home to some of the most amazing plants. One of these is the Ficus elastica tree, a sort of rubber tree that grows a ind of secondary roots from higher up in the trunk. The War-Khasis, a local tribe, noticed this plant and realized its potential.
Using hollowed-out betel nut trunks, the tribesmen are able to direct the roots in whatever way they like. When the roots grow all the way across a river, they are allowed to return to the soil, and over time, a strong bridge is formed. It takes up to 10-15 years for a root bridge to develop, but it becomes stronger with each passing year and are known to last for centuries.
Boulders and stones are placed among the rubber tree roots for an easier crossing. The living root bridges of Cherrapunji are incredibly sturdy, able to sustain more than fifty people at a time.
via rootbridges