Ancient sites in West Penwith are located where they are for a range of interlocking reasons - and these are reasonably consistent throughout the wider megalithic world. What exactly caused their builders to place them where they are is not exactly known, though here are some of the known factors that clearly seem to influence their decisions.
The placing of ancient sites
Several factors affect the location and design of ancient sites.
The Merry Maidens
Blind springs (called water domes in USA) are deep up-welling underground water-flows and seepages that hit an impervious rock layer below the surface and then spread out more or less horizontally and more or less radially from that point. These underground water-flows are detectable by dowsers by dint of the subtle energy created, which spreads out radially and also in spiral or energy-field patterns on the surface of the earth. Dierent dowsers will pick up diferent things, but their indings are usually congruent with each other.
This patterning has been shown to be a big factor in the location of standing stones, cairns and particularly stone circles, all of which have a water dome underneath them. Sites such as standing stones and cairns are often located at the crossing points of underground water lines - subterranean streams and trickles moving through fissures and porous areas of rock below. So there is a connection between ancient sites and earth energy - sites are located to mark, peg down, amplify or train flows of earth energy. This is how the theory goes. More about this here.
The visible landscape and intervisibility
The Britons of ancient times had their own form of feng-shui or landscape architecture. For example, both Tregeseal and Nine Maidens stone circles are overshadowed by prominent tors – Carn Kenidjak and Carn Galva respectively, both much used in neolithic times. The tors form a scenic backdrop to the stone circles.
There was a certain landscape artistry to this, and the building of a poetic and mythic psycho-geographical landscape, stuffed with character, history, hidden significances and spirit beings. So with many (but not all) ancient sites, their visual placing in the landscape is often important, and sometimes remarkable.
There's intervisibility too - seeing other sites from one site. For example, from Bosiliack Barrow, which is not on top of a hill, you can see Watch Croft (Penwith's highest hill, with barrow and menhir), Chûn Castle (hillfort), Carn Bean (barrows), Carn Kenidjak (neolithic tor), Botrea Hill (barrows), Bartinney Castle (enclosure) and Sancreed Beacon (cairns). This visible connection with other sites is important at some, but not all, sites.
Chûn Quoit from Boswens menhir
Some sites are on top of a hill (such as Bartinney Castle, Botrea Barrows or the cairns on Chapel Carn Brea) while others might be deliberately located on the side of a hill so that, when looked at from a particular site or location, they stand out on the horizon. This is the case for the menhir at Boswens, as seen from Tregeseal stone circle; or Chûn Quoit as seen from Boswens menhir; and for the menhir and cairn on top of Watch Croft, as seen from the Nine Maidens stone circle. If you stand at a site like Mulfra Quoit and swing around, you'll see an array of different sites and hills, some of them quite remarkably placed in relation to Mulfra. It's rather magical.
Sometimes, when approaching an ancient site, one wonders why it is located where it is. Then, when you arrive at the site a vista and visual context appear that suddenly makes sense, specifically at that precise location. If you move a short distance away this panorama or perspective disappears. So this siting business is at times really carefully calculated. Just above Carn Lês Boel, on the landward side, there is a small cairn which you can stand on, and Carn Kenidjack, some kilometers away, becomes visible - but move just a few yards off the cairn and it's gone.
The rising and setting points of the sun at the solstices and other key times of year such as the cross-quarter days, and those of the moon at its major and minor standstills, are important factors in the design and location of ancient sites. It probably applies also to the planets, but they follow more or less the same course as the Sun across our heavens, along the ecliptic, so it is impossible to tell whether their paths were specifically built into ancient sites. Some sites are oriented that way (such as the direction of the chamber in a chambered cairn), and at other sites a distant menhir or hilltop is aligned to a rising or setting point.
Summer solstice sunset as seen from Trencrom Hill
So the location of some sites was based on the viewing of rising and setting points. For example, from Chûn Quoit, the summer solstice setting sun sets in a nick in the summit of Carn Kenidjack, a kilometre away.
From Trencrom Hill, the summer solstice sun rises over St Agnes Beacon, up the coast, and sets in a nick between Trink and Rosewall Hills northwestwards, exactly following the incline of Trink Hill until it sets.
The mythic and cultural landscape
Every landscape feature had its own narratives, history and beliefs attached. These beliefs and mythologies often have some relevance to the nature of the site. Some prominent hills such as Carn Galva, Trencrom Hill or St Michael's Mount were regarded as the homes of giants, for which traditional tales of their antics still exist today. If I say "St Michael's Mount" to you, if you have seen it you will not only have an image of the Mount in your mind's eye, but also a bundle of impressions, associations, memories and narratives attached.
Trencrom Hill behind,Gull Rock in front. Taken from Porthtowan
Our perception of an area is still today influenced by traditions, stories and associations - about someone who lived there or something that happened - and this was very much the case for ancient people. Theirs was a magical landscape infused with presences and significances, and this wasn't just the fantasy of primitive people.
It was a magical perception with substance to it, that we need perhaps to reclaim now, to heal ourselves of a tendency to exploit and destroy nature and to exorcise the landscape of its spirits. It's a loveless condition that sees nature as a resource, a threat, or as a property with no emotional or imaginal content.
Ancient sites, with their special atmospheres, attract to themselves associations, mythologies, events and experiences both actual and numinous. Places have identity, and 'strong' places have characteristic atmospheres and resident presences - genius loci, the spirit of place.
This brings us to reality-fields. At some ancient sites, it feels as if you're at the centre of things - as if the world rotates around it - it's a focus of hereness. If awareness had gravity-centres where awareness is either drawn in or sent out, or each at different times, then we could regard this as a kind of gravitational 'reality field' - a bit like a magnetic anomaly, except a consciousness anomaly. If you walk round a magnetic anomaly with a compass, the needle will usually track the anomaly and forget magnetic north.
There is sometimes even a slight pulling feeling when one approaches an ancient site. The ancient Greeks called this an omphalos, literally meaning a navel. Whatever this reality field is, it is one of the things that pulls us to visit ancient sites and, when we get there, it's good to settle down, float off and be inside it for a while. Remember to take some essential geomancers' kit with you - a flask of tea and a flapjack.
These are very important, and a major theme on this website. The system of backbone alignments in particular is anchored to natural features such as tors, hills and headlands, influencing the location of major sites such as stone circles - so the site was built in alignment with pre-existing natural sites. These are focal sites. Subsequent or subsidiary sites are built in alignment with these - they are more derivative sites, at least in terms of alignment. Why exactly the megalith builders aligned sites to each other remains a mystery, but they did, and they invested great effort and accuracy in it. More about alignments here.
Mathematics and geometry
In other parts of Britain geometrical patterns, locational relationships and shapes have emerged in the way that ancient sites are located, and this is probably true in West Penwith too. Apart from a few such patterns (see here) this question has not yet been properly studied in West Penwith. It awaits someone to come along with that kind of brain.
Bundles of purposes
Many ancient sites are located where they are for a number of combined reasons, and what's remarkable is that this can be so. Sometimes it is not immediately visually obvious why a site is where it is. Chûn Quoit, Carfury menhir or even the Merry Maidens are examples: why are they on the sides of hills? Other sites are blindingly obvious, right on the top of hills - Lesingey Round, Chûn Castle or Castle an Dinas being examples.
But somehow, all of the above-mentioned factors knit together into a wholeness that determines the location and patterning of ancient sites. This is quite remarkable - some sites might have underground water, alignments, astronomical alignments and intervisibility as contributory siting factors, and what's remarkable is how they seem to interlock. Every site has a uniqueness to it, yet in an organic and intuitive way it follows similar rules to other sites. Usually a site exists not for one single neat reason.
When you visit them, it's good to go quiet, imbibing the feeling of a place, listening, hearing and seeing what it has to teach. What you 'get' isn't just imagination - you can pick up on something from the place-memory or the innate identity of the site, its genius loci or spirit of place.
The purpose of ancient sites
Mulfra Quoit from the Nine Maidens stone circle
Mounds (cairns, barrows and tumuli) sometimes show signs of use for burial of the dead, but this does not mean they were built for burial. Later in history, churches were surrounded with graveyards, though they were built to be houses of God, not primarily to host graves of the dead.
Both mounds and churches were built for a number of interlocking purposes, of which burying the dead was one, and really it was a secondary purpose. The primary purpose was geomantic.
Archaeologists tend to place undue weight on ancient burial practices, thereby missing other, more important, reasons why cairns and barrows were built. It is assumed that, since some mounds had burials and bones, all mounds must serve a funerary purpose. Not true. This is a bias.
In the 1960s-70s dowsers Guy Underwood and Tom Graves investigated this, coming up with the observation that mounds acted as energy batteries for the accumulation and release of energy, or as energy or information buffers, playing a part in a larger geomantic system.
Standing stones and stone circles, meanwhile, served as conductors or antennae connecting the earth and the heavens - acupuncture needles in the land. From an energy-engineering viewpoint, this makes these sites far more plausible and meaningful.
It would be wonderful to be able to read the minds of neolithic and bronze age people, to understand what was in their thoughts when building such a large number of sites as we see in Penwith, but we cannot - we can only see the signs and remains of what they did.
Here plausible speculation, intuition and imagination play as much of a role in understanding ancient sites as concrete archaeological evidence and its interpretation - which itself is sometimes invested with assumptions and guesswork that is not always correct. However, for speculation to be plausible, it does need to be supported or verified by further considerations that give more strength to it.
There can be a tendency to impose on ancient sites ideas and worldviews that come from modern times. The question of subtle energy and megalithic locational science is central to understanding megalithic remains, geomancers would say. But, since we moderns largely don't perceive subtle-energy impressions, and in many cases don't want to, subtle energy does not and cannot exist, and thus ancient sites can have no such connection or significance. It's simply woo-woo and hocus-pocus, and that wraps the matter up. Except that this is a time-limited belief.