"A team of restorers found the rooms behind a hidden door leading into the complex where Leonardo stayed in 1500."
So these students at the military school were so disciplined or busy that they didn't explore beyond the halls and rooms that had ready access. I guess my mind works differently. I like to get into the rooms, explore the nooks and crannies, find the quiet out of the way corners.
There is a report that the Mona Lisa is actually a SELF-portrait by da Vinci, but,-- well--, in drag. Compare the face to picture of the artist and you see the same shape and features. However most da Vinci pictures are of him as a much older, wrinkled man.