Discover Florence's Duomo

In addition to its sheer grandness, the dome is also an architectural marvel. It was the very first dome to be constructed, at least in Italy, without the aid of any framework. There are two layers to the octagonal dome, an inner piece that spans 42 meters (almost 138 feet, or about half of a football field) across and an outer shell that provides an amazing external view in addition to protecting the inner dome from weather damage.

Both the domes were built parallel to one another on stone ribs that taper from nearly 7 feet thick at the dome's base to 5 feet at the top, where a stone compression ring brings the ribs together. There are tie rings, oak timbers, and metal connectors to help maintain the dome's stability.

Atop the dome is a bronze ball placed there by sculptor Andrea del Verrocchio and his young apprentice. del Verrocchio and his apprentice used a hoisting machine to raise the ball, a machine designed by Brunelleschi. The apprentice, Leonardo di Vinci, is often credited for this hoisting machine invention.