The sign alludes to a scandal that involved Ms. Moratti during her last months as a mayor. Ms. Moratti's son Gabriele had bought a house on the outskirts of Milan and had done lots of construction works and the result reminded of Batman's Batcave. However, it turned out that the modifications made to the space were illegal and the problems were revealed when Mr. Moratti failed to pay the contractor who consequently sued him. It turned out also that Ms. Moratti had known about the works in Mr. Moratti's residence.