I have been looking at this geomancy thing when folks draw straight lines on flat maps to connect ancient sites.
After distances of around 11 miles the curvature of the earth becomes a factor and a straight line on a flat map would follow a completely different (radius) trajectory when plotted across the surface of a sphere. Long distance alignments across the planet would only be possible following lines across the circumferences on the sphere such as the equator or perpendicular north-south to the equator.
Hence, all these long distance 'sacred geometry' maps with lines connecting Stonehenge, to say Giza, are completely wrong and off by hundreds of miles. Even Stonehenge to Avebury would be tricky. But aligning objects around Avebury such as Silbury Hill is possible as the distance is short. This can be seen here in Sligo as the main megalithic sites are all visible from one another (and nearly all on top of mountains); so the ancient builders used line of sight. Therefore, locally it is possible.
I am not saying that ancient sites can't be aligned over relatively short distance, but over long distances they are completely incorrect when projected onto a flat map as the earth is a sphere. Every single 'sacred' alignments map I see is always straight lines on flat maps. They are wrong - all of them. A chap recently claimed that a pond in Cork is some 'sacred' site as it aligns with other sites all over the world, but again he made the mistake of using a flat map projection so it is all out by hundreds and hundreds of miles.
However, it is not all bad news. If researchers using correct mapping software which compensates for the earth's curvature, a whole new landscape of CORRECTLY aligned ancient sites may reveal themselves. Assuming this stuff is real to begin with.