The Dartmoor National Park in Devon covers 954m2 and the moorland is capped with granite outcrops dating from the Carboniferous Period. The moor contains many prehistoric remains dating back to the late Neolithic and early Bronze Age. Indeed, Dartmoor contains the largest concentration of Bronze Age remains in the United Kingdom. The large systems of Bronze Age fields cover an area of over 10,000 hectares (39 sq mi) of the lower moors.

One of the finest remains is the group of monuments at Merrivale. Side by side here are the remains of a Bronze Age settlement and a complex of ritual sites, including three stone rows, a stone circle, standing stones and a number of cairns or burial mounds. The monuments were probably built over a long period between about 2500 BC and 1000 BC.

The monuments at Merrivale comprise a group of round houses; two double stone rows and one single row; a small stone circle, with two standing stones nearby; and a number of cairns (earthen mounds), associated with burials. The large cluster of round houses is typical of a Bronze Age settlement. (The huge rounded stone here, often mistaken for a prehistoric chambered tomb, is in fact a post-medieval apple-crusher stone, used in the process of cider-making).

Stones and rows
South of the settlement and running east–west are two double stone rows, separated by a stream. Each row consists of more than 150 stones, most of them less than a metre high.
The northern double row is 182 metres (596 feet) long, with an average width between the rows of 1m (3 feet). The second row runs roughly parallel with the first but is longer, stretching 263 metres (865 feet) across the moor. It has terminal stones blocking each end. Near the middle of this row a ring of stones marks the kerb of a small cairn: this unusual feature may mark the burial of an important person.
A few metres south is a stone-lined burial chamber or cist with a massive, though damaged, capstone. Further west and just to the south of the row, a cairn marks the start of a single row of stones, running for about 40 metres (132 feet) at an angle to the double row.
To the west of these rows is a circle of 11 low-lying stones of local granite, about 18 metres (60 feet) in diameter. There is a tall stone, or menhir, nearby, which at more than 3 metres (10 feet) high is the most conspicuous object in the area.

It is quite possible that the ritual monuments of the Merrivale landscape belong to several different periods. How they might be related is a matter of conjecture, but such a vast array of monuments indicates that the site was of great spiritual importance to the people who lived in the area.
Running west of the site is the Great Western Reave, an earth or stone bank which probably represented an ancient field boundary. This is the longest of the many reaves which are a distinctive feature of Dartmoor, many of them stretching for miles across the moor.
Access: The site is one of the most accessible on Dartmoor, being close to a road in the middle of the moor. There is limited parking at the Four Winds car park off the B3357 and the settlement is a five minute walk from the car park. Be aware, however, that Dartmoor is known for its changeable weather conditions and this site is remote and very exposed. So come prepared.
Note
This information is taken from the English Heritage website and the text on that site is derived from the Heritage Unlocked series of guidebooks, published in 2002–6.
https://www.english-heritage.org.uk/visit/places/merrivale-prehistoric-settlement/history/
Text Alun Harvey
Sources English Heritage
Wikipedia