Rock art
The defining characteristic of rock art is that it is placed on natural rock surfaces; in this way it is distinct from artworks placed on constructed walls or free-standing sculpture. As such, rock art is a form of landscape art, and includes designs that have been placed on boulder and cliff faces, cave walls, and ceilings, and on the ground surface. Rock art is a global phenomenon, being found in many different regions of the world. There are various forms of rock art. Some archaeologists also consider pits and grooves in the rock known as "cupules", or "cups" or "rings", as a form of rock art.