Brunelleschi's dome of Florence Cathedral, ( S.M del Fiore), ca. 1422-66.
Brunelleschi died before the dome was completed,
and the Lantern was built by Verrochio.

The dome is constructed with an inner and outer shell,
held together with gigantic wooden beams and iron clamps.
Much detalied information is available online for the construction method
which includes specially made bricks for the dome's shells.
This constructuion can be seen when climbing the 463 steps to the top of the dome.

Note the visitors who have made this climb, who can be seen just beneath the lantern
in this picture. See next image for the entranace to the dome steps.