The Dome is one of the most significant architectural achievements of the Renaissance
A dome of the size and shape of the Florence Duomo that could support itself without collapsing was thought completely impossible to build before the Renaissance. In that time, they used a special herringbone brick pattern and a system of internal chains that ringed the outer dome like the metal rings on a barrel to help evenly distribute the weight.
The Dome has survived about 600 years, but a visit to the top isn’t for everyone
The dome has survived wars, storms, and multiple earthquakes.
Also, today visitors can climb the 463 steps to the tiptop of the dome for sweeping views of the city, but be warned, the Florence Dome climb isn’t for everyone. The stairs were originally built simply to help workers get up and down the cathedral walls for construction and maintenance; no one thought they would to be used by the general public. Not only are there hundreds of steps, but they are small, steep and narrow.