The stone circles are the best known of these monuments and have been researched the longest. Suggestions for their purpose include astronomy, calendar, cults, dancing and fertility rites. However, there is no explanation shown to apply to the majority of sites, let alone all the sites. It is therefore assumed that the circles were built for some ceremonial or religious purpose.
An astronomical purpose has not been generally proven except in a few specific cases. The alignments at Stonehenge relating to the sun and moon are well known. Also, the levelled horizontal stones in Recumbent Stone Circles (RSCs) are well positioned to observe the moon at its maximum standstill. The thought lingers that if these specific stones were for an astronomical purpose, then maybe other stones and circles relate to the stars.
Burials or cremations are often found in barrows. It is clear that many barrows and cairns were built for burial purposes during the Bronze Age because the burial is set centrally at the bottom of the cairn or on the ground below it. However, a few excavated barrows in Dorset have been proven to never have had a burial. There are also cases where a burial has been found but it was off centre and above ground level, suggesting it was not the primary burial. This situation leaves open the possibility that the original purpose of the barrow was not burial. An extreme example is Silbury Hill, which has now been proven to have no burial.
Burials are sometimes found at the other monuments, but not in a consistent manner.
This is especially true of the stone rows. On Dartmoor, many of the rows have a cairn associated with them. However, on nearby Bodmin Moor, the rows do not generally have cairns. Furthermore, there are hints that the Dartmoor cairns may be later than their row (e.g. Merrivale 3 row is clearly overlain by the cairn at its north end).
Given burials or cremations are not consistently found at the monuments, they have often been assumed to be ceremonial, processional, religious, and/or gathering places.
Even these ideas have difficulties because so many of the sites are almost barren of remains. Cursuses are notoriously void of remains. This led, along with the frequent lack of an entrance, to the idea that cursuses outlined sacred ground that needed to be kept clean. Most stone rows are similarly barren along the line of stones itself. If processions were part of the purpose of Cursus or row, it involved very few people. Circles are also low on remains, although several have evidence of charcoal.
On the other hand, causewayed enclosures and tor enclosures, often yield plentiful remains indicating sites that have been used for meeting, feasting, burial and defence. However, even here, there is no consistency in the way they were used. In other words, a common purpose for their construction is lacking.
It is therefore plain that we do not know with any confidence what any of these monuments were designed and built for.