Could we get some clarification on what counts as "construction beginning"? Technically speaking I'm pretty sure there's some startups already working on materials research with intent to use that to build a space elevator - I wouldn't want an answer to resolve yes as a result of hype around a company that has no chance of succeeding.

@spider I am defining it as the point where physical construction work starts. This means actual, tangible construction activities - like laying the foundational elements or 'bricks on the ground' - as opposed to preliminary phases such as materials research or design.