Root Bridges in India
While most famous bridges around the world are built, a Northeast region in India called Cherrapunji is famous for bridges that are grown. Yes, grown!
This part of India is one of the most humid and wet regions of the world which allows for an abundance of rivers and rubber trees. Bridges are grown over rivers by using a nut trunk to lead the root of the rubber tree in the right direction. The root will eventually go over the river and grow a root in the soil, on the other side of the bridge. In time, the bridge will become sturdy enough to allow about 50 people at a time. Some bridges are over 100 ft long and it takes about 10 to 15 years for a bridge to be fully grown and safe for villagers to use.
Source: The Root Bridges of Cherrapunji