… The root bridges, some of which are over a hundred feet long, take ten to fifteen years to become fully functional, but they’re extraordinarily strong – strong enough that some of them can support the weight of fifty or more people at a time.
In fact, because they are alive and still growing, the bridges actually gain strength over time – and some of the ancient root bridges used daily by the people of the villages around Cherrapunji may be well over 500 years old. …
atlas obscura – THE ROOT BRIDGES OF CHERRAPUNJI
I saw that linked from The Long Now Foundation. That page has a good video describing how local people build these living bridges.
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