In Cherrapunji, India, one of the wettest places on Earth, the locals mould the roots of the Ficus elastica tree into stretching across rivers and taking root on the other side, forming amazing natural, living bridges.
Locals use hollowed-out trunks of the betel tree to prop up the roots of the Ficus elastica (basically a rubber tree), pointing them across whatever body of water they want to cross, until the roots reach the other side and dig in. After a while (a long while — think 10-15 years), the bridge becomes strong and sturdy enough for people to comfortably walk across. Some of these bridges are hundreds of years old since they just get stronger over time being alive and all. Pretty amazing stuff. [Living Root Bridges via Reddit]