Like San Vitale and the Hagia Sophia, the geometric shape that is the central plan for the Dome of Rock is c. Octagon
The Dome of the Rock, like San Vitale and the Hagia Sophia, is built on an octagonal plan. This geometric shape was often used in religious architecture during the Byzantine and Early Islamic periods, as it was seen as a symbol of perfection and stability.
The octagonal plan also allowed for the construction of a large, centrally placed dome, which was a key feature of these monumental buildings.
The octagonal plan also has symbolic meaning in Islam. The number eight is associated with the eight directions of the compass, representing the divine omnipresence and unity. The octagon also represents the eight gates of paradise.