The Grey Cairns of Camster are two large Neolithic chambered cairns in the Highland region of Scotland. They are among the oldest structures in Scotland, dating to about 5,000 years ago. The cairns demonstrate the complexity of Neolithic architecture, with central burial chambers accessed through narrow passages from the outside. They were excavated and restored in the late 20th century and are open to the public.
The cairns were constructed in the third or fourth millennium BC in a desolate stretch of boggy peat-covered moorland in the Flow Country of Caithness. They consist of two structures standing 180 m (590 ft) apart, known as Camster Round and Camster Long. Although the surrounding countryside is now inhospitable and sparsely inhabited, during the Stone Age it was fertile farming land and only became covered in peat during the Bronze Age.