It's just a series of variations on the head of the Duke of Montefeltro, who's a great, great figure in the Renaissance, and probably the basis for Machiavelli's "The Prince."
Son una serie de variaciones sobre la cabeza del duque de Montefeltro, que es una gran, gran figura del Renacimiento, y, probablemente, la base para "El Príncipe" de Maquiavelo.