The Cairn of Barnenez is a Neolithic monument located near Plouezoc'h, on the Kernéléhen peninsula in northern Finistère, Brittany (France). It dates to the early Neolithic, about 4800 BC. Along with the Tumulus of Bougon and Locmariaquer megaliths, also located in Great West France, it is one of the earliest megalithic monuments in Europe and one of the oldest man-made structures in the world. It is also remarkable for the presence of megalithic art.

Megalithic art refers to art either painted or carved onto megaliths in prehistoric Europe. Elizabeth Shee Twohig has coined the term Megalithic art in her study of 'The Megalithic Art of Western Europe'. Her original definition of Megalithic art focused on paintings or carvings found on the structural elements, like the kerbstones, orthostats, or capstones of megalithic tombs, but recent investigations have included decorations on stelae and menhirs.