Megaliths are large stones that have been used to construct prehistoric structures or monuments, either alone or together with other stones. They were used for a variety of purposes, ranging from serving as boundary markers of territory to being reminders of the past. Megaliths are found all over the world, with over 35,000 in Europe alone. They were erected between the Neolithic period through the Chalcolithic period and into the Bronze Age.

There are different types of megaliths, including menhirs, dolmens, stone seats, stepped stone pyramids, and various types of stone circles. In South Asia, megaliths of all kinds are noted, including menhirs, rock-cut burials, chamber tombs, dolmens, stone alignment, stone circles, and anthropomorphic figures. These are broadly classified into two classes: sepulchral, containing remains of the dead, or memorial stones where mortal remains along with funerary objects are placed; and non-sepulchral, including large patterned placement of stones over a wide area.

Megalithic monuments were typically decorated with a variety of Stone Age art, including petroglyphs, various abstract signs and symbols, pictographs, motifs, cupules, cup and ring marks, and other incised imagery. Typical patterns used in this ancient art included spirals, zigzags, and other types of abstract art.

Examples of megalithic structures include Stonehenge in England, the dolmens of Carnac in France, and the menhirs of Brittany. Megaliths have also been found in South Asia, Iran, Iraq, and Israel.