A Sanskrit word (मण्डल) Mandala, meaning 'Circle' - so as you would imagine the overall structure is circular. The Mandala design itself traditionally holds on to a number of design rules and parameters, and leaves room for individual embellishment.
The traditional symetry of a mandala is four-fold, containing four 'gateways'. But I feel that any symetry will do the trick! In this way, other avenues of thought - such as Sacred Geometry can more easily come into play. The Mandala, is in fact, a 'Cosmogram' - a diagram that represents all that is, all that can be, and the entire cosmos in an abstract way.
So the diagram represent not just the self - and the progress of the self (which Jung was so interested in) but also, it represents the family and extended human and animal familly; the town, city, continent or world.
The mandala is a symbol of great religious and philosophical interest. Mandalas of various styles are used in religious practice all over the world. For meditation, initiation, prayer and contemplation.