Walking out of the Pitti Palace and observing the backdrop of old buildings on the western side of the square, you will note on the right, a large building with a yellow facade, the result of centuries of building transformations. On this site, as the plaque walled to one side of the entrance portal reads, stood the houses where sources say Paolo dal Pozzo Toscanelli lived, the famous author of the letter sent to Christopher Columbus in which he claimed that the shortest way to reach India was to navigate westwards. Toscanelli was the author, around 1475, of the gnomon on the Dome of Santa Maria del Fiore, till then the highest one ever built, which made it possible to verify the moment of the Sun’s passage through the summer solstice.