The dome of Florence Cathedral Santa Maria del Fiore had been designed by Arnolfo di Cambio in 1296. The planned octagonal dome was the biggest both in terms of length and width of its kind and presented several challenges that delayed its construction. In di Cambio's project there were no external buttresses to sustain the weight of the dome. This indicated a change in the architectural taste as external buttresses were typical Gothic features and were rejected by Renaissance principles. Without the butresses the dome would surely collapse, so, when the building started, Brunelleschi planned an inner and an outer dome to hold up the structure. The outer dome was built with bricks which are lighter than marble and inside the inner dome Brunelleschi placed a set of four horizontal chains made of iron and stone, functioning as hoops, and a fifth one made of wood between the first two chains.
In addition to architectural problems, there were also problems regarding how to move the large amount of materials needed to such height. To this end, Brunelleschi invented a new hoisting machine.