The Cathedral of Santa Maria del Fiore features a large dome without flying buttresses by using a combination of architectural and engineering techniques. The dome is supported by a series of hidden arches and a double shell structure, with the inner shell supporting the weight of the dome itself and the outer shell providing additional support. The dome's shape also helps to distribute the weight evenly. Additionally, the cathedral's bell tower and apse provide additional support to the dome. Overall, careful design, construction, and use of various architectural features allow the Cathedral of Santa Maria del Fiore to have such a large dome without the need for flying buttresses.