The Brazilian Stonehenge.

It challenges one's mental image of the size of the world to think that something like this could exist and not have been noticed until now:

A total of 127 large blocks of stone were found driven into the ground on top of a hill.

Well preserved and each weighing several tons, the stones were arranged upright and evenly spaced....

The stones appear to have been laid out to help pinpoint the winter solstice, when the sun is at its lowest in the sky.