Did mankind understand the size of the spherical earth to an astonishing degree of precision many thousands of years ago? Here is a link to a fascinating discussion of the analysis presented by Jim Alison at his website, entitled "The Prehistoric Alignment of World Wonders: A New Look at an Old Design."
Mr. Alison presents evidence that ancient sites including the Giza pyramids, Ollantaytambo, Nazca, Easter Island, and many others are all located along a single great circle centered on a point in Alaska. This is a startling assertion, as these sites are clearly very widely distributed geographically, and the massive monuments located at each site, while sharing some remarkable similarities, are also thought to have been the products of cultures separated in time by many centuries or even millennia.
Even more remarkable are the relationships that he demonstrates between many of these sites, such as his finding that Ollantaytambo (in Peru) is 108° along the great circle from Giza (in Egypt). As he points out, 108 is an extremely significant number, and the location of these historic sites 108° apart is unlikely to be a coincidence (the idea that all the location of all these sites along a great circle of the globe could be a coincidence is likewise extremely unlikely -- when we find that two of the sites are separated by 108° along a global great circle, the possibility of coincidence becomes even more remote).
The number 108 is an important precessional number, as is the number 72, which Mr. Alison demonstrates to be operating between Giza and other sites. He notes in a different article on the same subject, this one published on Graham Hancock's website, that Giza and the site of Angkor Wat in Cambodia are very nearly 72° apart along the same great circle, and that Easter Island (Rapa Nui) is located at a point on the circle that is very nearly equal angles of arc to Angkor going in one direction and Giza going in the other. Mr. Hancock also discusses the significant separation angles of various sites around the globe (including Rapa Nui, Angkor, and Giza) in his gorgeous book Heaven's Mirror (and movie of the same name).
Also extremely significant is the fact that Easter Island / Rapa Nui is located directly across this great circle from the Indus Valley. This relationship (as well as the one discussed above for Angkor, Rapa Nui, and Giza) can be easily seen in the diagram of the great circle on this page of Mr. Alison's essay (bottom diagram on that page). The mysterious (and as-yet undeciphered) writing systems of both of these sites (Rapa Nui and the Indus Valley) are almost certainly related. The undeciphered script of the Indus Valley is generally known as the "Indus Valley Script" and the undeciphered writing of the tablets found on Easter Island (preserved, in fact, by the people living there when the first European ships arrived) is known as "Rongo Rongo" (and the tablets known as "Rongo Rongo Tablets"). The similarities between these mysterious writing systems -- separated by half the globe along this great circle discovered by Mr. Alison -- can be clearly seen on this web page comparing the two writing systems.
The idea that these sites could be completely unrelated and just somehow happen to lie upon the same great circle of the globe -- at significant intervals on that circle, including angles of arc corresponding to clear precessional numbers -- is ridiculous. When evidence such as the similarity of the Rongo Rongo Tablets to the Indus Valley Script is added to the discussion, the case for a connection becomes even stronger. Also note the very strong evidence at Ollantaytambo for a connection with other ancient sites across the oceans which was discussed in this previous post.
Not only does this analysis by Mr. Alison argue for an ancient connection of some sort between all these sites, but also that mankind knew the size and shape of the earth in great antiquity -- long before the conventional timeline of human history says that humans could have had such precise scientific knowledge. As he says on page 10 of the article on Graham Hancock's website:
Many similarities between these sites have been well documented, including the use of perfectly cut and precisely placed monolithic stones, exact orientations to the cardinal points and astronomical orientations. The prevailing view of world history dismisses these similarities as coincidental developments of separate stone age cultures. Unless it is also a coincidence that these sites are located at mathematically and geometrically significant points on a single line around the center of the Earth, it may be time to reconsider the idea that Europeans of the present era were the first to know the size and shape of the Earth.
Here is a different website (which refers to the work of Mr. Alison) presenting other evidence that an ancient culture or cultures knew the size and shape of the earth quite well, and deliberately positioned significant sites around the globe as a sort of world-wide web of coordinates or reference points.
Mr. Alison presents even more additional evidence to support the conclusion that the ancients knew the size and shape of the earth with great precision. He points to other great circles which can be drawn through other significant ancient sites, such as another great circle that connects the Great Pyramid and the Serpent Mound of Ohio and other ancient significant sites (Ross Hamilton presents extensive analysis using completely different evidence which appears to support a connection between the Great Pyramid and the Serpent Mound in his amazing book The Mystery of the Serpent Mound: in Search of the Alphabet of the Gods).
All of this analysis appears to be very strong supporting evidence for the conclusion that mankind in the very ancient past had a very sophisticated level of knowledge and scientific achievement (and that they could and did travel over the entire globe), an assertion put forward in the Mathisen Corollary book as well (supported by different evidence and analysis) as well as in many other previous posts on this blog (for instance, here and here). While the monuments currently located in some of those sites may have been erected much later, it is fairly clear that many of those points along the great circles found by Mr. Alison (including Giza, Malta, and the Indus Valley) are of extreme antiquity, and thus it is quite likely that this system of worldwide coordinates is very ancient indeed.