Ovoo

Ovoo, oboo, or obo (Mongolian: овоо, pronunciation  , Buryat: обоо, Khakas: обаа, Traditional Mongol: ᠣᠪᠤᠭ᠎ᠠ, "heap"; Chinese: 敖包 áobāo, lit. "magnificent bundle [i.e. shrine]") are cairns used as border markers or shrines in Mongolian folk religious practice and in the religion of other Mongolic peoples. While some ovoos simply consist of a mound of stones, most have branches and khadag stuck into them. In the absence of stones, ovoos can be made entirely of branches, or even soil or sand.

Ovoos are often found at the top of mountains and in high places, like mountain passes. In modern times, some of them have developed into large and elaborate structures, becoming more like temples than simple altars. They serve mainly as sites for the worship of Heaven and lesser gods led by shamans and kins' elders, but also for Buddhist ceremonies.