Final answer:
Brunelleschi's double-walled system using lightweight bricks made building the Great Cathedral's dome possible. This invention provided support and shifted the weight outwards to the dome supports, allowing for its construction without the need for a temporary wooden structure.
Step-by-step explanation:
Brunelleschi's invention that made building the Great Cathedral's dome possible was a double-walled system using lightweight bricks. The dome was built 43.2 meters high and employed a herringbone brick design spiraling upwards to add support and shift the weight outwards to the dome supports. Brunelleschi also designed and created numerous hoisting machines to lift the materials to the workers. This invention allowed for the construction of the dome without the need for a temporary wooden structure.