It's difficult to know just what you are asking but one of my favourite measurement stories belongs to a guy named Eratosthenes who lived in Alexandria in the third century BCE.
In 240 BCE using the method detailed at this link he calculated the Earth's circumference with extraordinary accuracy. The unit of measurement he used was the stadion (plural stadia) but there were two measurements using that name in the ancient world and he may have used either one. Consequently we don't know whether he was off by 16% (an extraordinary effort) using one form of stadion, or by an incredible 1% using the other form.
He's one of history's giants.
