It was truly amazing even walking toward this iconic cathedral There are countless videos, books, etc on how the dome was constructed, so I won’t reiterate the details here – but this is what Wikipedia has to say, in case this area is new to you:
“Florence Cathedral, formally the Cattedrale di Santa Maria del Fiore (Italian pronunciation: [katteˈdraːle di ˈsanta maˈriːa del ˈfjoːre]; in English Cathedral of Saint Mary of the Flower), is the cathedral of Florence, Italy (Italian: Duomo di Firenze). It was begun in 1296 in the Gothic style to a design of Arnolfo di Cambio and was structurally completed by 1436, with the dome engineered by Filippo Brunelleschi.[1] The exterior of the basilica is faced with polychrome marble panels in various shades of green and pink, bordered by white, and has an elaborate 19th-century Gothic Revival façade by Emilio De Fabris. The cathedral complex, in Piazza del Duomo, includes the Baptistery and Giotto’s Campanile. These three buildings are part of the UNESCO World Heritage Site covering the historic centre of Florence and are a major tourist attraction of Tuscany. The basilica is one of Italy’s largest churches, and until the development of new structural materials in the modern era, the dome was the largest in the world. It remains the largest brick dome ever constructed. The cathedral is the mother church of the Archdiocese of Florence, whose archbishop is Giuseppe Betori. The unreinforced masonry that Brunelleschi used to construct the dome is weak in tension which leads to cracking when tensile stresses exceed the limited masonry tensile strength. The material is especially susceptible to damage from seismic loading due to its heterogeneity and many surfaces between different materials (stones to mortar connection).[40] Cracking of the dome was observed even before its construction was completed. It is possible that the first cracks were caused by a strong earthquake in 1453.”
