1½ miles West of Brinian, Rousay, Orkney, Scotland.
Blackhammer is a stalled chambered cairn situated just over a mile to the West of Brinian on the island of Rousay, along a stretch of the B9064 which is teeming with ancient monuments, including the Broch of Midhowe, and the cairns of Midhowe, Taversoe Tuick, and the Knowe of Yarso.
Blackhammer has suffered considerable damage over the millennia with much of the stonework which once formed its roof being robbed for building material. Consequently its external appearance now owes more to the restoration project which followed its excavation in 1936, resulting in the mostly unaltered chamber being covered with a large protective shell of concrete, on top of which is a broadly rectangular grassy mound measuring 72 x 27 feet. In its heyday it would have looked entirely different, with a slabbed roof capping the chamber and a great heap of small stones arranged on top of it. The dry stone walls which form its sides still exist but are sadly now hidden beneath the mound, as is a low lying outer wall which extends some five feet beyond it. The stonework of the latter takes the form of a quite elaborate and carefully constructed pattern of triangular-shaped sections of dry stone walling, slotted together likes wedges of cheese (see plan). This pattern bears a striking similarity to Unstan ware pottery of the same period, circa 3,000 BC (see here). When the cairn finally fell out of use, the people who sealed the entrance took care to blend their stones into the surrounding wall, and did such a good job that the 1936 excavators were unable to identify it until they entered the chamber and worked their way outwards.
The entrance passage on the southern side of the mound is 10 feet long, yet very cramped at just over 2 feet wide and 3 feet high. Not that this matters for modern visitors as it has been blocked off, with a window set above it to permit observation, although at the time of my visit this was acting as a sort of greenhouse with a great mass of foliage thriving beneath it. The chamber is now accessed via a short ladder under a sliding metal door in the roof, directly above where the passage begins to emerge into the interior.
Inside is a 42 feet long and more or less 5 feet wide rectangular chamber aligned on an East-West axis. The raised concrete roof presents no headroom problems for any but the unnaturally tall, and while it cannot be said with any certainty what the original height was, it may have fluctuated from 5 feet at the extremities to just 2 feet in the centre judging by the uprights along its length. Six pairs of these uprights protrude from the walls and divide the chamber into seven similarly-sized compartments, although four to the West of the entrance are missing. On the northern face, directly opposite the entrance, is a heap of stacked stones. A larger heap is on the southern face immediately to the West of the entrance, and this latter originally extended across to the northern face, thereby blocking access to the three western-most compartments. Both of these stacks are later additions to the cairn, but when they were introduced and what purpose they served remains a mystery.
The skeletons of two adult males were discovered; one in the western-most chamber and the other half way along the entrance passage. It is likely that these were just the last to be interred before the cairn was sealed up and abandoned, and that others had been present in earlier times but were removed to permit new burials. Bones of sheep, ox, red deer, pink-footed goose, cormorant and gannet were also found, together with pottery fragments, pebble and flint scrapers, a flint knife, a bone pin, and a finely polished grey-green stone axe.
Archaeology Data Service - Excavation Report