MadSci Network: Astronomy |
The short answer is that nobody knows for sure. Ancient builders didn't document their methods, and very little has come down to us today. Presumably this sort of information was conveyed directly from master to apprentice.
That isn't to say, however, that we can't make some educated guesses about how it could be done. Ancient peoples were lacking in technology, and in depth of knowledge, but they weren't lacking in intelligence; they were as clever then as we are today. Ancient structures with astronomical alignments are found in the British Isles, Egypt, Mesoamerica, India, and other places. Some date back thousands of years; obviously these engineering problems were solved independently many times.
Ancient engineering technology is a subject now taught at many universities. The basic approach is to define a problem and consider its solution given only the tools and knowledge available to a given people. Probably the best known example was a series of experiments made by the PBS television show NOVA several years ago in an effort to understand how Egyptian obelisks were raised.
Many people consider ancient structures such as you describe to reflect remarkable skills, but I've never thought so. After all, an alignment of the Sun on a particular day with some architectural element is easily determined with a scale model, or by roughing in part of the structure with wood before committing to stone. These techniques don't require any particularly advanced skills.
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