Barrow (from A.S. beorh, a mount or hillock), a word found occasionally among place-names in England applied to natural eminences, but generally restricted in its modern application to denote an ancient grave-mound. The custom of constructing barrows or mounds of stone or earth over the remains of the dead was a characteristic feature of the sepulchral systems of primitive times. Originating in the common sentiment of humanity, which desires by some visible memorial to honour and perpetuate the memory of the dead, it was practised alike by peoples of high and of low development, and continued through all the stages of culture that preceded the introduction of Christianity. The primary idea of sepulture appears to have been the provision of a habitation for the dead; and thus, in its perfect form, the barrow included a chamber or chambers where the tenant was surrounded with the prized possessions of his previous life. A common feature of the earlier barrows is the enclosing fence, which marked off the site from the surrounding ground. When the barrow was of earth, this was effected by an encircling trench or a low vallum. When the barrow was a stone structure, the enclosure was usually a circle of standing stones.

Sometimes, instead of a chamber formed above ground, the barrow covered a pit excavated for the interment under the original surface. In later times the mound itself was frequently dispensed with, and the interments made within the enclosure of a trench, a vallum or a circle of standing stones. Usually the great barrows occupy conspicuous sites; but in general the external form is no index to the internal construction and gives no definite indication of the nature of the sepulchral usages. Thus, while the long barrow is characteristic of the Stone Age, it is impossible to tell without direct examination whether it may be chambered or unchambered, or whether the burials within it may be those of burnt or of unburnt bodies.

In England the long barrow usually contains a single chamber, entering by a passage underneath the higher and wider end of the mound. In Denmark the chambers are at irregular intervals along the body of the mound, and have no passages leading into them. The long barrows of Great Britain are often from 200 to 400 ft. in length by 60 to 80 ft. wide. Their chambers are rudely but strongly built, with dome-shaped roofs, formed by overlapping the successive courses of the upper part of the side walls. In Scandinavia, on the other hand, such dome-roofed chambers are unknown, and the construction of the chambers as a rule is megalithic, five or six monoliths supporting one or more capstones of enormous size. Such chambers, denuded of the covering mound, or over which no covering mound has been raised, are popularly known in England as "cromlechs" and in France as "dolmens" (see Stone Monuments). The prevailing mode of sepulture in all the different varieties of these structures is by the deposit of the body in a contracted position, accompanied by weapons and implements of stone, occasionally by ornaments of gold, jet or amber.

Vessels of clay, more or less ornate in character, which occur with these early interments of unburnt bodies, have been regarded as food-vessels and drinking-cups, differing in character and purpose from the cinerary urns of larger size in which the ashes of the dead were deposited after cremation.

The custom of burning the body commenced in the Stone Age, before the long barrow or the dolmen had passed out of use. While cremation is rare in the long barrows of the south of England, it is the rule in those of Yorkshire and the north of Scotland. In Ireland, where the long barrow form is all but unknown, the round barrow or chambered cairn prevailed from the earliest Pagan period till the introduction of Christianity. The Irish barrows occur in groups in certain localities, some of which seem to have been the royal cemeteries of the tribal confederacies, whereof eight are enumerated in an ancient Irish manuscript, the Leabhar na h-Uidhri, compiled c. A.D. 1100. The best-known of these is situated on the banks of the Boyne above Drogheda, and consists of a group of the largest cairns in Ireland. One, at New Grange, is a huge mound of stones and earth, over 300 ft. in diameter and 70 ft. in height. Around its base are the remains of a circle of large standing stones. The chamber, which is 20 ft. high in the centre, is reached by a passage about 70 ft. in length. In the Loughcrew Hills, Co. Meath, there is a group of about thirty stone barrows or cairns, mostly chambered, their bases measuring from 5 or 6 to 60 yds. in diameter.

They are unusually interesting from the fact that many of the exposed slabs in the walls of the chambers are ornamented with spirals and other devices, rudely incised. As in the case of the long barrows, the traditional form of the circular, chambered barrow was retained through various changes in the sepulchral customs of the people. It was the natural result of the practice of cremation, however, that it should induce a modification of the barrow structure. The chamber, no longer regarded as a habitation to be tenanted by the deceased, became simply a cist for the reception of the urn which held his ashes. The degradation of the chamber naturally produced a corresponding degradation of the mound which covered it, and the barrows of the Bronze Age, in which cremation was common, are smaller and less imposing than those of the Stone Age, but often surprisingly rich in the relics of the life and of the art workmanship of the time. In addition to the varied and beautiful forms of implements and weapons - frequently ornamented with a high degree of artistic taste - armlets and other personal ornaments in gold, amber, jet and bronze are not uncommon. The barrows of the bronze period, like some of those of the Stone Age, appear to have been used as tribal or family cemeteries.

In Denmark as many as seventy deposits of burnt interments have been observed in a single mound, indicating its use as a burying-place throughout a long succession of years.