A monumental mound is a large conical-shaped mound of earth and stone, of prehistoric date, often carefully constructed with internal revetments, surrounded by a substantial quarry ditch and in some cases an outer bank, the whole structure being in excess of 150m in diameter. Most lie near to henge- enclosures.

Monumental mounds are usually recognized as up-standing earthworks or, when heavily denuded, from antiquarian sources. It is possible that examples will be recognized through aerial photography by the presence of the large and characteristic ditch, but such components are common to several other classes of monument and it is unlikely that aerial photography alone will bring these sites to light.

Monumental mounds may potentially be confused with large round barrows of various classes (especially bowl barrows) but these rarely exceed 45m in diameter and are therefore generally rather smaller than the monumental mounds. Other sources of confusion include the mottes of medieval motte-and-bailey castles and prospect mounds in post-medieval gardens. These can usually be distinguished by their fresh and recent appearance and the presence of related components. Some monumental mounds were, however, reused as mottes or propspect mounds in recent times which means that great care must be taken in the identification and classification of these sites.

Specifically excluded from the class of monumental mounds are the large roughly hemispherical prehistoric burial mounds which contain stone or wooden burial chambers, and which are generally rather smaller than monumental mounds anyway.

Monumental mounds appear to have been ritual or ceremonial monuments of late Neolithic date closely related to the henge and henge-enclosure traditions of southern England.