The Cairn of Barnenez (also: Barnenez Tumulus, Barnenez Mound etc.; in Breton Karn Barnenez; in French: Cairn de Barnenez or Tumulus de 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; it is considered one of the earliest megalithic monuments in Europe, as well as the oldest building in the world.