As you head east from Stromness, a bridge crosses the inlet linking the Bay of Ireland to the Loch of Stenness. Just to its east is the junction at which the direct road to Kirkwall diverges from the road via Orphir.
And a few yards further a signposted track heads north to a parking area near a farmhouse on a promontory projecting into the Loch of Stenness. From it a path leads the hundred yards north to the Unstan Chambered Cairn.
Unstan Cairn was constructed by our neolithic ancestors on land just a few feet above the level of the Loch of Stenness, a site that leaves you wondering about the movement of sea levels since it was built some 5,000 years ago.
Unstan is a stalled cairn. Within the grassy mound and under the modern roof which protects the interior, vertical slabs divide a roughly rectangular chamber into three central compartments and two end compartments: and a side chamber opens from the west side of the main chamber. Visitors gain access via the original entrance, which is low enough to require a grovel rather than a crawl.
The cairn was excavated in 1884 and 1934. Human bones were found in all the stalls of the main chamber, while two crouching skeletons were found in the small side chamber. Also found were a number of flint tools, plus parts of at least 35 pottery bowls.
The bowls were of a very distinctive type, since found in many Orkney tombs, and now known as Unstan Ware. These were produced from local clay and finely finished long before the advent of the potter's wheel.
To the north of the cairn it is just possible to make out a double line of ramparts and ditches cutting across the tip of the promontory, presumably as a means of defending it. Nothing is known of the origin or date of this feature.