A Neolithic astronomical device
Maeshowe is a chambered cairn constructed around 2800 BCE on the island of Orkney. The entire structure is a grass-covered mound 7.3 meters high and 35 meters in diameter, which contains a stone-built interior. The builders used massive, flat slabs of local flagstone, some weighing up to 30 tons, to construct the tomb with remarkable precision. A single passage, about 11 meters long, leads to a central chamber that is roughly a 4.6-meter square. Three smaller cells branch off from this main chamber.
The structure's most significant scientific feature is its precise solar alignment. The entrance passage is oriented so that for several weeks around the winter solstice, the light of the setting sun shines directly down its length. This beam of light illuminates the rear wall of the central chamber, a deliberate astronomical orientation also seen in other Neolithic passage tombs, such as Newgrange in Ireland. This alignment with the sun on the shortest day of the year shows a sophisticated understanding of celestial mechanics by its Neolithic builders. The light's path also aligns perfectly with the Barnhouse Stone, a large standing stone located about 700 meters away.