The Wheel

The Wheel is the central space designated for the Great Circle. Each of the Mages of the Great Circle has an office and connected workroom within the Wheel, with painted doors in their own ranked colors opening onto a curving outer corridor. There is also a meeting hall for the Circle mages to meet, and a reinforced room for testing applicants. The cellar of the Wheel is where the Shard of Elan is housed, supporting the magical shield which hangs over most of Chrenada.
The Wheel sits within the greater Naziar complex within the city of Alham. It is not a part of the palace itself, but a separate building loosely connected with the military grounds. The Great Circle is considered a part of the state, but it is not technically a part of the military, so it sits independently but with easy access to and by officers.
The Wheel is built of Stone and Alternatives for maximum resilience to the magic it houses.

Architecture

The Wheel is built of stone, a sensible precaution in a building for magical experimentation. Combustion is kept safely confined. Mostly. Any candidate testing for entrance to the Circle is expected to have the control necessary to demonstrate their skills safely even within the Wheel's testing rooms.
(The apprentice trials are held outdoors, in a stone-walled courtyard, just in case.)

Type

Ministry / City hall