Una stella nel Battistero di Pisa

A computer analysis on the reverberation characteristics of Pisa Baptistery and the studies about the symmetries of the Monuments of the whole Piazza dei Miracoli in Pisa by the american mathematician David Speiser, led to the discovery of a suggestive reference frame used for designing and building the Baptistery: everthing here is based on the golden number, the regular pentagon and, finally, a star.