Researchers think they ' ve found Leonardo 's ` ` The Battle of Siena '' Pigment found on a hidden wall with ` ` Mona Lisa '' paint , they say . The city of Florence asked the Italian government to do more study . The theory is that when artist Giorgio Vasari created his mural `` The Battle of Marciano , '' he erected a brick wall in front of da Vinci 's plaster wall , effectively preserving the older masterpiece . ` The wall is in the Hall of the 500 of the Palazzo Vecchio , the seat of Florence government .
Researchers think they ' ve found Leonardo 's ` ` The Battle of Siena '' Pigment found on a hidden wall with ` ` Mona Lisa '' paint , they say . The city of Florence asked the Italian government to do more study . The wall is in the Hall of the 500 of the Palazzo Vecchio , the seat of Florence government .