Florence

The Florence skyline is dominated by the cathedral of Santa Maria del Fiore, called Il Duomo by the Italians, topped by Brunelleschi's dome.

An excerpt from the article 34 facts about Florence

Brunelleschi’s design involved building the largest dome ever built at the time and the first larger dome built in Europe since the two great domes of Roman times - the Pantheon in Rome and Hagia Sophia in Constantinople.

The red dome of Santa Maria del Fiore remains the largest brick structure of its kind in the world.