The Monarch of the Plain (Amesbury 55) is a very large Bronze Age bell barrow which survives as an earthwork. It comprises a circular mound which sits on a sloping berm, surrounded by a ring ditch. The monument stands 2.8m above the surrounding ground level and measures a maximum of 58m in diameter. Excavation by Colt Hoare (Barrow 40) in the early 19th century found only charred wood. The barrow was listed by Goddard and Grinsell as Amesbury 55. The round barrow was surveyed at 1:1,000 scale by English Heritage in March 2010 as part of the Stonehenge WHS Landscape Project. It has been damaged by burrowing rabbits and early 20th century vehicular activity.
The largest round barrow on Salisbury Plain. This Bell Barrow was opened by Hoare on more than one occasion but all he reported finding was charcoal and no interment. The Barrow has a sloping raised berm.
No.40, in point of size, may be called the monarch of the plain, being evidently the largest barrow upon it; and its history still remains veiled in obscurity. The first time we opened it by a very large section, and examined well the floor ; but though we perceived symptoms of cremation, in charred wood &c. we could not discover the primary interment. Nor were our subsequent researches more favourable, and we still remain in ignorance. Perhaps some future antiquary may be more fortunate; and such is the caprice of ancient sepulchre, that the deposit may be found near the top, as in the instance of our flint barrow at Kingston Deverill, (p.47).
The Ancient History of Wiltshire Vol 1, Hoare, Sir R.C. 1812 - Page 164