A distinctive class of late Neolithic ceremonial enclosure found throughout the British Isles, dating mainly to the middle and later 3rd millennium bc, perhaps with origins among the formative henges. Roughly circular in plan, henges are bounded by a bank, usually with an internal ditch. They have a single entrance (Class I), two diametrically opposed entrances (Class II), or, exceptionally, four entrances (also Class II). Some examples have a second ditch outside the bank (Class IA/IIA). Single henges as well as groups of three or four examples near together are known. Henges frequently contain a scatter of pits, occasional burials, circular settings of posts, or stone circles. The largest example is at Avebury, Wiltshire, in southern England. Also known as classic henges. See also henge enclosure; hengiform monument.