“An expert medieval weaver might need an hour to complete one square inch of a tapestry, which meant that in a good week he might finish a patch maybe eight inches on a side. The weavers were generally young men, and each Unicorn tapestry likely had a team of between four and six working on it. They wove only by daylight, to insure that the colors were consistent and not distorted by candlelight. One tapestry would have taken a team at least a year to complete.”

from the New Yorker