What are these two men

What are these two men observing in Piazza Duomo?
 

Two XIX century statues sculpted by Luigi Pampaloni are situated near the bell tower of Giotto in Piazza S. Maria del Fiore. They are Arnolfo di Cambio and Filippo Brunelleschi. The two statues have been placed here in 1830 during the renovation of the whole square by Gaetano Baccani who built three different palaces for the canons.
The two architects Arnolfo di Cambio and Filippo Brunelleschi seems astonished: in fact they are looking at the works of art they created a few century before.
Arnolfo projected the Cathedral of Santa Maria del Fiore; works started in 1296 under the direction of the great architect who was involved in the same years in the edification of the Priors palace, the church of S Croce, the florentine abbey, the lodge for the sale of grain. So he is looking down because he is admiring his church.
Brunelleschi, on the contrary, is looking the sky: he was the man who enriched the city of Florence through the construction of the dome in 1436. Brunelleschi left no texts or documents to explain how he did to create the covering of the church, a self supporting structure separeted from the rest of the building by a drum. Even the genius Leonardo studied it and reproduced wooden models of the machines Brunelleschi employed to move the material he needed! Simply fantastic!