Stone Circles
In flat biomes (such as plains and desert) you may find a stone circle constructed from cobblestone and stone. Some of the stone pillars may have a Runestone on the top. With the proper tools and some study, these runestones can help you reach distant locations.
Stone Circles are usually found quite close to each other but if you are in a forest or mountainous area you may have to travel quite far to find one.
In the Outerlands
If you find a stone circle in The Outerlands there is chance that there will be Vaults beneath them. Vaults contain some of the greatest treasure and artifacts that Strange has to offer, hidden inside a large labyrinth of corridors and rooms, patrolled with illagers and challenging mobs. Read more about the Vaults here.
Notes
With permissions enabled, you may search for the closest stone circle by using the command /locate strange:stone_circle.