Octagon: represents 8 straight sides. Eight denotes the intermediary region between earth and heaven or, the microcosm, between body and spirit; and the octagon is a symbol of the “best” part of psychic substance that is the vehicle of spiritual light or ether.
The octagon expresses the nearness to heaven of the psychic element (ether or space), and by being almost circular in form it expresses all, but spiritual completeness.
This “nearness to heaven” has been translated in houses of worship and sacred places in history throughout the world.
The Dome of the Rock has a characteristic octagonal plan. The Tower of the Winds in Athens is another example of an octagonal structure. The octagonal plan has also been in church architecture such as St. George’s Cathedral, Addis Ababa, Basilica of San Vitale (in Ravenna, Italia), Castel del Monte (Apulia, Italia), Florence Baptistery, Zum Friedefürsten church (Germany) and a number of octagonal churches in Norway.
The central space in the Aachen Cathedral, the Carolingian Palatine Chapel, has a regular octagonal floorplan. Uses of octagons in churches also include lesser design elements, such as the octagonal apse of Nidaros Cathedral.
Architects such as John Andrews have used octagonal floor layouts in buildings for functionally separating office areas from building services, notably the Intelsat Headquarters in Washington D.C., Callam Offices in Canberra, and Octagon Offices in Parramatta, Australia.