What took the Jews 8 days to produce new oil when rededicating the Temple in the Chanuka story? It seems the process of oil-making takes a lot less time (I have done it in Israel on one of the tourist trips), so what exactly historically took 8 days?
Another answer (Beis Yosef, Orach Chaim 670, s.v. והטעם) is that the actual pressing would indeed take a day, but that they first had to undergo seven days of purification (from tum'ah contracted by contact with corpses, of which there were plenty during the battles against the Syrian-Greeks) - since, after all, the whole point was that they needed oil that was free of tum'ah.
The Ran in Mesechtas Shabbos 21: and the Rokayach in Hilchos Chanuka say that it took 4 days to travel to the location where they made the oil and 4 days to travel back, hence 8 days. The Meiri in Mesechtas Shabbos 21: says that the place where the oil came from was Tekoa.