Some recent examples confirm Head's rule - that the best place to look for ancient manuscripts is in a library (previous examples include P52, Luther's lectures on Romans, the Archimedes Palimpsest):
The discovery of an ancient Torah scroll in an Italian university library (mis-catalogued)
The discovery of a letter by Robert the Bruce in the British Library
The discovery of an ancient Torah scroll in an Italian university library (mis-catalogued)
The discovery of a letter by Robert the Bruce in the British Library