One of the most common observations about Leonardo da Vinci's 'Mona Lisa' is that the subject appears to have no eyebrows or eyelashes. For years, people believed this was because it was the fashion of the time for women to pluck them all out. However, in 2007, ultra-high-resolution scans by engineer Pascal Cotte revealed that Leonardo had indeed painted them. Cotte found a single brushstroke of a single hair above the left eye. He concluded that the eyebrows and eyelashes were originally present but had faded over centuries or were accidentally scrubbed away during poor cleaning and restoration attempts in the past. This discovery highlights the delicate nature of Renaissance oil paintings and the role of modern technology in uncovering the original intentions of the Old Masters.