A Bronze Age turf covered bowl barrow, considered to be the largest on Exmoor. It measures 34 metres east to west by 32.8 metres, and 2.7 metres high. The centre has been robbed leaving an irregular hollow.

Longstone Barrow lies southeast of the Longstone, from which it gets its name. [1] There are traces of surrounding ditch at Longstone Barrow. A circular pit has been dug on top of the barrow. It is scheduled with two other barrows. [3] Longstone Barrow is a bowl barrow with a hollow in the top and enclosed by a ditch. It is 34 paces in diameter and 8 feet in height. [6] Longstone Barrow is located at SS 7072 4277. It is a ditched bowl barrow, 42.6 metres in diameter and 3.7 metres high. It has a large 0.9 metre deep central mutilation and the ditch is almost filled with peat marsh. Resurveyed at 1:2500. It is shown as very substantial on the 1979 NMR aerial photograph, which also shows the ditch and outer bank. [7,8] This is a Scheduled Monument, part of Devon 237 (The Longstone Barrow group). [10] Longstone Barrow is located at SS 7073 4277. This turf-covered bowl barrow, possibly the largest on Exmoor, is very prominently situated at about 475 metres above Ordnance Datum, on the western edge of a ridge containing at least five other large barrows. There are panoramic views; northwards to the Bristol Channel and the South Wales coast, eastwards to Wood Barrow and the Chains Barrow, southwards to Five Barrows, and westwards across to the Chapman Barrows, Barnstaple Bay and Hartland Point. It measures 34 metres east/west by 32.8 metres, and is 2.7 metres high. Some stone content could be felt on probing, but it is predominantly of earthern construction. The barrow appears to have been deliberatly constructed with a distinct change of slope about 1.6 metres high, some 5 to 6 metres in from its periphery. The centre has been robbed leaving an irregular hollow about 6 metres in diameter and 1.5 metres deep. The spoil has been dumped around the hollow forming a ring of material about 12.5 metres overall diameter and about 0.5 metres high, giving a false 'cap' to the barrow, which increases its original height of some 2.7 metres to 3.2 metres. A surrounding ditch, about 5.5 metres wide and 0.3 to 0.5 metres deep, is still evident around most of the circumference. It is best seen around the southeast, where its outer scarp is up to 0.7 metres high. The northeast quadrant is mainly silted up and there is a slight mutilation on the western rim. There is no evidence of an alleged outer bank on aerial photographs [8] as stated by Fletcher. [11] The Longstone Barrow and surrounding ditch is clearly visible on aerial photographs, partiularly the infra red photography taken for Exmoor National Park Authority in 1981. There is no trace of the alleged outer bank on the photographs examined as part of the Exmoor National Park National Mapping Programme, however, the NMR 1979 photographs referenced above were not available for the survey in 2008. [13-16] The Scheduled Monument Condition Assessment of 2009 gave the site a survival score of 0. [17] The site was surveyed in March 2015 as part of the 2015 Exmoor Scheduled Monument Condition Assessment. It was given a survival score of 7. [18] The barrow was subject to geophysical survey as part of a wider study of a group of monuments on Challacombe Common in June 2015. Magnetically, the ditch returned a negative response, suggesting it had been dug into magnetically sterile subsoil or geology with little enhancement from the surrounding area to produce a response. The results also suggest that the original barrow mound was later enlarged and enhanced at a later stage. This is perhaps a togographic affect as the mound has a clear shoulder. [19]