Over the past four years, I've been a devoted viewer of Clickspring, the YouTube channel of an Australian clockmaker named Chris. The main project Chris has been working on over that time is reconstructing a working Antikythera Mechanism using as much of the tools and techniques as was likely used in its original construction.
For those who may not know, the Antikythera Mechanism is one of the most amazing discoveries of the ancient world. It is a (likely) Hellenistic-era (late 2nd century BC) analog calendar computer that could track solar, lunar, and astrological movements and even track the 4-year cycle of the Olympic-like games of the period.
In Chris' reconstruction of the device, he encountered issues with the long-held idea that one of the calendar rings was an Egyptian "civil calendar," a non-lunar calendar of precisely 365 days, comprised of twelve 30-day months (plus five epagomenal or "intercalary" days). In this paper, in the Journal of the British Horological Institute, Chris and fellow researchers "provide new data to show this interpretation to be incorrect, and displace the century-long assumption of a 365-day calendar on the Antikythera Mechanism, proposing instead that it is a 354-day lunar calendar."
It is so inspiring to see how amateur practical archeology can lead to these sorts of upending discoveries.