The Watchstone is a megalith standing approximately 5.6m tall, situated at the south end of the Brodgar Bridge overlooking the Loch of Stenness. It is located in close proximity to the Stones of Stenness. Originally, there were at least two stones there, as in the 1930s the stump of a second stone was discovered. Various theories exist, suggesting that the Watchstone might have been part of a larger circle, or that other stones may have existed linking Stenness to Brodgar, but all of these remain unproven.

It's unfortunate that this stone stands right next to the road, but nevertheless, the location is breathtaking. The Stones of Stenness are clearly visible to the south-east, and the locks of Stenness and Harray flank it on either side. On a clear day, the views are incredible.