It was the great achievement of the Byzantine architects Isidorus and Anthemius, to transfer the weight of the dome to the pillars using arches and pendentives, the four triangular sections of masonry that fill the gaps between arches and dome, to create the illusion of an unsupported dome floating in space.
Isidorus and Anthemius made the dome look like it was floating in space by using arches and pendentives to support it.
The architecture style Isidorus and Anthemius favored makes it very clear that the dome is supported by arches and other structures.