The Amazon River has no bridges crossing its main stem.
Why it is true
Despite being the second longest river in the world, the Amazon basin is predominantly composed of dense forest and scattered riverside communities. The lack of major roads and the variable width of the river make bridge construction impractical and unnecessary.
Source: National Geographic
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.