A long barrow is a prehistoric monument usually dating to the early Neolithic period. They are generally about 5,500 years old and among the oldest architectural structures ever built. They are traditionally interpreted as a collective tomb.
They are rectangular or trapezoidal tumuli or earth mounds. Long barrows are also typical of several Celtic, Slavic, and Baltic cultures of northern Europe of the 1st millennium AD.
In recent years the construction of barrows seems to have undergone a revival.
The totality of the function of long barrows is not known, and perhaps can never be known.
It is clear they were used as funerary monuments at the time they were built.
It is also understood that this use continued more or less formally for many thousands of years after, remains being placed at the sites or into the earth of the monuments for many centuries.
It has been speculated that they also had cultural roles linked to the re-assignment of roles, for example within the domestic-type roles that existed (such child rearing) in setting of high rates of death in child birth, and also the farming and other practical tasks which would have required redistribution to different members of the community upon the death of one of its members.
They contain bones of many individuals, which often show evidence of regular moving around or sorting. This is known to have happened at West Kennet Long Barrow in Wiltshire, for example.
It appears the structures were accessed regularly, not just to inter newly deceased bodies but also to make use of the old bones there. It is possible that bones were taken out of the barrow for some purpose and returned later. Some authors speculate that this was part of an ancestor veneration practice.
In the present-day there is a parallel custom observed in the Famadihana tradition found in Madagasgar.
Modern tillage techniques have done much damage to barrows. According to English Heritage, in the last six decades as much as traditional tilling did in six centuries.