At a lunar backsight where permanent or temporary ancillary extrapolation gear has been set up there should be a length preserved between major stones which is the 4G for this site. This 4G represents, on the ground, the lateral distance an observer must move in order to 'shift' the Moon through the declination range K. K is the change in the Moon´s position during the 24 hours preceding a standstill. At a Major Standstill it is 46.5 arc minutes and at a Minor Standstill 30 arc minutes. See also- K, ANGULAR DISPLACEMENT, EXTRAPOLATION PROCEDURE, LUNAR STANDSTILL.
The largest man- made mound in Europe stands 39 metres high by the River Kennet in Wiltshire. Although it is an impressive statement in the landscape it can not be viewed from any aspect at distances greater than 500 metres or so as it sits on low ground by the river.
This enigmatic monument has been the subject of much debate and speculation. No burials nor cavities have been found despite several tunnels and shafts sunk into and through the heart of the construction. No ancillary settings or earthworks with clear associations have been identified in the surrounding territory. See: http://www.english-heritage.org.uk/daysout/properties/silbury-hill/