Dounreay Castle

Dounreay Castle is located at the mouth of the Mill Lade immediately north of the Dounreay licensed site. 

It dates from the late 16th century, and is one of the few remaining examples of a Scottish Laird’s castle from that period.

William Sinclair of Dunbeath, descended from a younger brother of John Sinclair, third Earl of Caithness, built the castle in the 1560s.

It was damaged in 1651 by Oliver Cromwell’s New Model Army during their Scottish campaign.

Now entirely ruined, the castle was still inhabited in 1863, but had become roofless and derelict by 1889.

Due to its significance both in Caithness and nationally as a surviving example of an unusual design of L-shaped fortified tower house more typical of lowland Scotland, it has been designated by Historic Scotland as a scheduled monument.

Dounreay Castle and photo gallery

Concern about castle condition

Remediation project

Experiments involving radioactive liquids were conducted from the castle courtyard in the 1950s, using a temporary holding tank and pipeline. As a result of leakage and spillage, the courtyard became affected by radioactive contaminants. The tank and pipeline were removed, but it was impossible to decontaminate the site conventionally, given its archaeological sensitivity.

Contaminated drainage water had also leaked through fractures in the Castle Gate drain, contaminating the coastal slope and beach area.

In 1996, UKAEA began a two-year project to characterise and remediate the area in order to reduce the possibility of contamination migrating towards the marine environment, while preserving the castle’s archaeological heritage.

The project team took samples from the castle and beach areas to establish the baseline condition of the site. After discussions with Historic Scotland, the site was excavated in close co-operation with a team of archaeological specialists. This allowed safe removal of contaminated material and enabled the archaeologists to develop and record a detailed understanding of the site’s archaeological history.

An area of 900m3 was excavated down to a maximum depth of 3m, creating 1,540 tonnes of low-level waste. This was safely transferred to the Dounreay site’s waste storage facilities, and the excavated areas were backfilled with non-contaminated fill from local farms and quarries, and segregated materials from site excavations.

Following the remediation work, the project team carried out a radiological survey, which showed that levels of residual contamination did not present a significant health or environmental risk.

The remediation works allowed open access to the site for the first time in 40 years, and have helped to preserve an important feature of Scottish archaeological heritage.

Historic Scotland Ancient Monuments report on condition of castle

In 2008 DSRL staff noticed a deterioration in the structure of the castle which caused concern both for the safety of personnel and the heritage aspect of the building.

Scheduled Monument status requires the owner (or his agent) to inform Historic Scotland of any perceived deterioration and not to undertaken any work within the area that may cause further damage to the monument. 

Dr John Malcolm, Inspector Ancient Monuments NW Team, carried out an inspection of the structure in early February 2008.

DSRL has now received an inspection report from Historic Scotland which contains some recommendations for the preservation of the Castle, and DSRL intends to consult with the conservation agency on the long-term interests of the monument.  There is no element in the 1979 Ancient Monuments and Archaeolgical Areas Act which compels landowners to care for monuments.

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Dounreay Castle


Dounreay Castle is situated on the foreshore at Dounreay and at the mouth of the burn known as the Mill Lade.


The castle has been derelict and roofless since the late 1880s


Following the successful decontamination of the castle in 1997-1998, a cairn and plaque were erected in the castle courtyard