A long mound is a low sinuous bank of earth and/or stone, in some cases flanked on either side by a ditch, of rectangular plan, and typically between 40m and 140m in length. One or other of the ends may be connected to, or closely associated, with some other class of Neolithic ceremonial/ritual monument. Long mounds are recognized mainly as earthworks, often because of their associations with other monuments, or, in the case of ditched examples, as flat sites revealed by aerial photography or through excavation.
Long mounds have variously been confused with long barrows and bank barrows, but can usually be distinguished on the basis of their overall size (bank barrows are much longer and more substantial; the ditches of long barrows are much bigger), the scale and shape of the mound (which is low and of uniform height in long mounds), and the absence of formal burial areas such as occur in most types of long barrow. Other possible sources of confusion include pillow mounds and segmented portions of banks forming components of various other classes of monument.
Specifically excluded from the definition of long mounds are those monuments which are actually bank barrows but which have sometimes been called long mounds as an alternative name, and long barrows which have had their mounds extended by the addition of a "tail".
Long mounds are generally interpreted as ceremonial or ritual monuments of Neolithic date. Their exact function is, however, unknown, and while they may be associated with monuments directly related to the burial and celebration of the dead there is no firm evidence that any long mounds themselves were necessarily connected with such activities.