A Long Barrow is a type of prehistoric burial mound found primarily in Europe, particularly in the British Isles. These structures are typically elongated and made of earth and stone, serving as tombs for the dead. They date back to the Neolithic period, around 4000 to 2500 BCE, and often contain multiple burial chambers. Long Barrows are significant archaeological sites that provide insight into ancient burial practices and social structures. They are often aligned with astronomical events, suggesting that the builders had a deep understanding of their environment. Examples include the West Kennet Long Barrow and the Silbury Hill.