The dome of Florence Cathedral, built by Filippo Brunelleschi between 1420
and 1436. It measures 41 metres across inside and rises to 116 metres
counting the lantern. It has a double shell (an inner cover and an outer
one tied together by buttresses) and is built of brick laid in a herringbone
pattern, a Roman technique Brunelleschi worked out again for himself. Until
then, closing the octagonal hole over the crossing was considered
impossible, and it had stood open to the weather for almost a hundred
years.
