The one about the cupola of which Joseph Brodsky wrote: “The enormous egg that Brunelleschi laid brings tears to an eye long used to the glitter.”
By the way, the cathedral foundation stone was laid by the Cardinal of Florence on behalf of the Pope long before the birth of Filippo Brunelleschi. It took exactly one hundred and forty years to complete the cathedral, which was consecrated in 1436.
Brunelleschi, an exceptional architect and an engineer, one of the fathers of the Italian Renaissance, was among those who completed the cathedral. In the meantime, he brushed off the allegations of his ties to the devil by using a cracked egg he placed onto the tip to prove that the top can be spanned without pillars. He also established the patent business. Anxious over slowness of the marble slab loading, Brunelleschi not only invented a shipboard rotating crane but also was the first to secure his copyright. A great architect of the Quaradrocento was very witty in securing the firmness of his creation. He made a small hole in the cathedral’s cupola and built a small plate into the floor. If the light going through the hole falls onto the plate at noon on 21 June, the next year will be good. If the light misses the plate, look for cupola or foundation displacement. And start repairs before the disaster happens.