In this escapist diary, I consider the standing stones of northwestern Europe, particularly in Britain and Ireland. The most famous example of these monuments is Stonehenge, in Wiltshire. Wikipedia has a fine article on Stonehedge. I'd like to emphasize some of the things about this structure which are not commonly understood.
From a distance the structure appears to be simply a crude circle of stones, with some perched precariously on top of the others. In fact, the entire work is one of extraordinary craftsmanship. At a distance, the monument seems insignificant, but at close range, the great size of the upright stones becomes apparent.
The monument was not built all at once, but rather over the course of approximately 900 years. it went through several forms, and most curiously some of the earliest works were among the most sophisticated.
Archaeological investigation has disclosed that Stonehenge was constructed in several phases, which ran over the course of about 1,000 years, beginning between 3000 and 2500 BCE. These phases have been divided into Stonehenge I, Stonehenge II, and Stonehenge III.
Stonehenge III
The construction of Stonehenge III constitutes the most prominent portion of the work now visible. This consists of the the remnant of a complete ring of thirty upright stones, of a type of rock called "sarsen", which is found approximately 20 miles away at the Marlborough downs.
Connecting completely around the top of the stone uprights was a complete circle of stones, called "lintels". The elevated circle thus formed is known as an architrive. The lintels were not simply set atop the upright stones, like a child might set up a set of building blocks. Rather, each upright had projecting tenon laboriously carved out of the stone, as is well shown here and here.
Each one of the upright stones, both of the outer ring and of the trilithons, was worked into shape. This image, from the excavation that was done in the 1950s, well shows the masterful shaping of the trilithons. During the 1950s, several stones which had fallen were returned to their original positions; the modern work (shown for example here, here, and here) was a significant undertaking, which can convey some idea of the difficulty of construction of the project over 4000 years ago.
In Hardy's novel Tess of the Durbervilles, the heroine Tess Darbyfield, supposed it is said of an ancient line of nobility, is found sheltering at Stonehenge. Perhaps Hardy had in mind this natural hollow in one the uprights (later filled in with concrete to prevent the stone from toppling over.
The overall effort necessary to construct Stonehenge III necessarily implies a high level of social organization.
Stonehenge I.
As impressive as is Stonehenge III, it is the much earlier work of Stonehenge I which demonstrates, at least arguably, an extremely high level of observational and mathematical skill.
Stonehenge I consisted of the following features. A circular ditch 297 feet in diameter was excavated around the area within which the later erected sarsen circle now stands. The material excavated from the ditch was piled inside the ditch to make a dike, which as a result of erosion over the years, is now only about 1 foot high on the average.
There gap in the ditch and dike ring called the "avenue" which is pointed in the direction of the sunrise and sunset on midsummer's day. The avenue extends for a considerable distance beyond the monument. At the approximate center of the avenue is a large unshaped stone, currently leaning over, which is called the Hele Stone (Stone 96).
Just inside the ditch and dike are four "stations" which form an almost perfect rectangle. Two stations are built on mounds, and would be in considered to be in opposite corners of the rectangle. The stations (called 92 and 94) appear to once have had stones set upright within them but no stones are present there today. Two other stations (called 91 and 93) are not built on mounds but do continue to have upright stones, which are unshaped and about 3 feet high.
About 10 feet within the ditch is a ring of 56 holes about 3 feet wide, which were discovered by John Aubrey (1626-1697), and which are consequently called the Aubrey holes.
An ancient observatory?
The astronomer Sir Fred Hoyle, most famous for his "steady-state" theory of the Universe, and for the invention of the term "big bang", also did a rather thorough study (Stonehenge Decoded -- anyone interested in the scientific method should read this book, which is less than 200 pages in length), on whether Stonehenge I could have been used as analog computer to predict lunar eclipses, which were considered portents of disaster or other ominous news by ancient peoples. See this gif for an example of the dramatic effect of a lunar eclipse.
Hoyle established, I believe quite convincingly, that Stonehenge could have been used as both an observatory as well as eclipse calculator, with the Aubrey holes playing an important marker role.
However, for the whole system to work, it would have be recalibrated at least twice at year, at midsummer's day and midwinter's day. In addition, the swings of the rising and setting moons would have to be carefully tracked and recorded. Hoyle believed this could have been done using the Station Stones as sight lines, and using posts across the entrance to the monument as markers.
Of course, whether Hoyle is right can never be known, and it is largely a matter of taste. If you believe that stone age cultures had the intelligence to track, record and ultimately predict complex celestial movements, then you will be inclined to agree with Hoyle, and vice versa.
The Rudstone Monolith
But the uprights at Stonehenge are not the largest menhirs in Britain. That place is held by the Rudstone monument far away from Stonehenge in the East Riding of Yorkshire. This stone stands 26 feet above the ground (its tip is protected from erosion by modern metal sheeting), and it appears that it may extend just as deeply below the ground -- an extraordinary depth of excavation for a prehistoric work. A curious detail about this site is that it is in the graveyard of the very old Rudston Parish Church. The siting of the church in this location appears to have been an effort to christianize the heathen stones by the early missionaries in Britain, and indeed the name "Rudstone" comes from the Anglo-Saxon word "rod" which meant rod in general and "cross used for crucifixion" in particular, as used in the title of the very early Anglo-Saxon poem The Dream of the Rood.
Carnac
Near a small village in Brittany named Carnac stand multiple parallel rows of large standing stones. This monument was erected between 4500 and 3000 BCE. Of the 3,000 stones which are estimated to have existed in prehistoric times, only 700 remain now. However, like Stonehenge, this monument is unique. While a variety of theories exist as to the purpose of the monument, none of them are particularly satisfactory.
Er Grah
Also in Brittany, near Quiberon Bay, can be found Er Grah, sometimes known as the Great Broken Menhir is actually a fallen single standing stone that has broken into four pieces. Intact, this stone would have measured some 67 feet long and would have weighed 280 tons. The stone has been traced to a site several kilometers away. It is believed to have been erected sometime about 4700 BCE, and it is the largest stone ever set up by prehistoric humans. There are other megalithic monuments close by. The whole complex seems to have been in existence and use for a very long time. As with Carnac, a number of theories have been advanced to explain its purpose, but other than the rather obvious possibility that these were religious in nature, there is no very persuasive one.
Other monuments
There are so many interesting megalithic sites which I could mention, and perhaps readers can name a few.
* In Ireland, north of Dublin, there is a rather different type of monument called New Grange, which is called a "chambered tomb." As with Stonehenge, there are a large number of other ancient sites nearby.
* Not far from Stonehenge lies the enormous monument of Avebury. This site has many interesting features. It is composed of a high berm circular in shape, which might lead to the conclusion that this would have been intended as a defensive work. However, the ditch from which the material for the berm was excavated is inside the bank, rather than on the outside. The site is so large that it is estimated that 250,000 people could stand within it, although whether such number could be assembled in ancient Britain remains speculative.
* A fascinating and little-known monument is Thornborough Henges in north Yorkshire. This consists of a chain of three round berms,called "henges" connected by an "avenue", with the whole structure being over a mile long. Although there are no standing stones, this is still a striking monument. Like so many megalithic sites, its purpose is unknown.