The dome of Florence Cathedral was designed and engineered by Filippo Brunelleschi between 1420 and 1436 following a contest in 1418-19 for a design.
The opening for a dome had been capped on completion of the cathedral due to problems with a design to span such a large space.
Brunelleschi's design incorporates two shells, one within the other, linked by oak beams and iron braces, to support the weight and thrust of the massive structure.
The dome's height is 375 feet, and the span is 176 feet. Visitors can climb the original steps between the dome shells that were used by the workers building the dome.
After making the climb to the top, a visitor can walk around on the lantern topping the dome, which was completed by Michelozzo following Brunelleschi's death.
The bronze ball and cross topping the lantern were Verrochio's design and completed in 1469. Brunelleschi also designed a crane for lifting materials to the worksite.
Many of Brunelleschi's tools can be seen in the Museo del Duomo across the street from the Duomo's back side.