How did architects create elements in the dome of Hagia Sophia (in Istanbul) that float higher than any previous dome?

Hagia Sophia is a religious building in Istanbul, Turkey.

Explanation:

"Hagia Sophia" is known for its amazing architecture means, "holy wisdom". It is famous for the huge dome and relics of nails of 'Jesus' and 'Shroud' of Mary.

Initially, the weight of the dome was an issue as a series of earthquakes caused the dome to collapse. But then it was reconstructed. Architects had re-build the entire interior walls to make it stronger and robust to back the dome's weight.

"Pendentives" (in form of spherical triangles) were used as a structural transition between the base which was of square shape and the dome which was of round shape. This way the load was transferred to the base walls and the ground.

The "pendentives" made it feasible to position the dome placed upon a square compartment.