Mysteries get marked by blue icons on the world map. You can find this Cairn Mystery on top of a mountain southwest of Dublin.
You have to arrange the stones so that they stay upright to reach the designated height. Arrange the stones so that they rest on each other and do not fall. There can be multiple ways to arrange the stones like one below.
- Grab the largest and thickest stone and set it to make the base of the Cairn
- Grab the stone (upper left) and carefully place it on top to reach the height.
- Grab the stone (upper right) and rotate it vertically and place it to reach the desired height.