Dyffryn Ardudwy is located in the northwest of Wales in the Gwynedd region, 40 m above sea level on the flat slope of Moelfre in an area enclosed by a wall and a forest area at the edge of the village, which gave it its name. The excavation in 1960 revealed a well-preserved two-phase monument. First, a small chamber was built, which lay in an oval cairn or a low platform with a forecourt. The small chamber consists of six support stones that support a capstone. In front of the portal, the parts of several Neolithic vessels, the type of fine simple "Irish Sea Ware" were found in a pit. Later, a second chamber was built east of the first one. This chamber also has a modern concrete pillar to support the larger capstone. The chamber had a porch containing battered pottery. Neolithic and Bronze Age ceramics were also found inside the chamber. Some of the vessels contained dark soil with a concentration of cremated bones that belonged to a single individual. Seven flints were found between the stones of the Cairns and a broken arrowhead lay at its eastern end. Both chambers of Dyffryn Ardudwy were ultimately integrated into the common stretched very shallow Cairn or enclosed by a low platform. But it is possible to recognize the shape and size of the original smaller oval Cairns, which was initially built around the western chamber. Nearby is the Cairn of Cors y Gedol.