Crosskirk Broch

People were already settled on the headland by the end of the Bronze Age, and the early Iron Age that followed left behind carinated pottery (vessels with a sharp shoulder or ridge) that appears to have been made locally yet closely resembles wares from the same period in southern and eastern England. Uncorrected radiocarbon dates place some of this pottery, including a few black-burnished sherds, in the sixth and fifth centuries BC.

A discontinuity in the middle Iron Age saw the buildings reconstructed and new types of pottery and other artefacts introduced alongside variants of the older styles, a change that has been read as evidence of an influx of new and influential people. Local pottery-making nonetheless continued in the same tradition through the period when Rome occupied southern Scotland, between roughly 80 and 180 AD, and Roman pottery and glassware reached the site, whether through trade or other contact.

Radiocarbon evidence dates the construction of the broch itself, a large circular stone tower, to around 200 BC, raised inside the earlier promontory fort's rampart so that it would have loomed above the older defensive wall. It included a guard cell, a chamber built within the thickness of the wall, and a stair entrance at ground level, but the wall's core of earth, rubble and boulders made for a weak, experimental design that could never have supported a tower as tall as later examples.

External houses clustered around the tower from about the time it was finished, forming a small village of a kind otherwise found only in northern Scotland, while the broch remained in use into the second century AD despite repairs that never fixed its underlying weakness. A final rebuilding in the second century preceded abandonment, by which point defence seems no longer a concern, and a body was buried sitting upright in one of the round buildings around this time, without grave goods.

Long after the broch had fallen out of use, two cist burials (stone-lined graves) were dug into its debris at some point around 600 AD, showing the mound was still being used as a burial place centuries later. A stone carved with runic lettering once stood at Crosskirk, dating from the age of Norse raiders active around Caithness in the ninth, tenth and eleventh centuries, though the stone itself has since been lost.

St Mary's Chapel was built about 30 yards, roughly 27 metres, south of the broch mound around the 13th century, and the ground to the south of the older site was deliberately levelled to make way for it. In more recent times some of the stones from the broch mound were taken away, likely for building field dykes, gradually reducing what remained visible above ground.

A description recorded in 1871 measured an internal diameter of roughly 30 to 32 feet and a wall 14 to 15 feet thick, noting a probable entrance breach on the south side, while a 1964 survey found the wall reduced to little more than a metre high, already exposed by erosion. Coastal erosion continued to undercut the cliff, and between 1966 and 1972 Fairhurst and Taylor excavated the ruin before it was bulldozed over the edge, the site grassed and a memorial cairn erected in its place.