The early history of Caithness may, to some extent, be traced in the character of its remains and its local nomenclature. Picts' houses, still fairly numerous, Norwegian names and Danish mounds attest that these peoples displaced each other in turn, and the number and strength of the fortified keeps show that its annals include the usual feuds, assaults and reprisals. Circles of standing stones, as at Stemster Loch and Bower, and the ruins of Roman Catholic chapels and places of pilgrimage in almost every district, illustrate the changes which have come over its ecclesiastical condition. The most important remains are those of Bucholie Castle, Girnigo Castle, and the tower of Keiss; and, on the S.E. coast, the castles of Clyth, Swiney, Forse, Laveron, Knockinnon, Berriedale, Achastle and Dunbeath, the last of which is romantically situated on a detached stack of sandstone rock. About six miles from Thurso stand the ruins of Braal Castle, the residence of the ancient bishops of Caithness. On the coast of the Pentland Firth, 1½ miles west of Dunscansbay Head, is the site of John o' Groat's house.

See S. Laing, Prehistoric Remains of Caithness (London and Edinburgh, 1866); James T. Calder, History of Caithness (2nd edition, Wick); John Home, In and About Wick (Wick); Thomas Sinclair, Caithness Events (Wick, 1899); History of the Clan Gunn (Wick, 1890); J. Henderson, Caithness Family History (Edinburgh, 1884); Harvie-Brown, Fauna of Caithness (Edinburgh, 1887); Principal Miller, Our Scandinavian Forefathers (Thurso, 1872); Smiles, Robert Dick, Botanist and Geologist (London, 1878); H. Morrison, Guide to Sutherland and Caithness (Wick, 1883); A. Auld, Ministers and Men in the Far North (Edinburgh, 1891).