Shri Chakra

Also called S(h)ri Yantra, the Shri Chakra is a sacred Indian cosmological diagram consisting of 9 isosceles triangles, 5 downward pointing (representing 5 aspects of the Shakti - the primordial divine feminine power) and four pointing upwards (representing four aspects of Shiva - the primordial unmanifest masculine principle) forming a structure of 43 triangles, representing 43 deities, or aspects of the Self. 

The central diagram is enclosed within two lotuses, the inner of 8 petals, and the outer of 16 petals. Then three concentric circles. Around this is the bhupura (palace of the Earth) with four gates representing the four directions of space.

At the centre of the diagram is a dot known as the bindu, which represents the undivided Self, beyond the duality of male and female.

The Shri Chakra was described by Shri Shankaracharya, in his Soundarya Lahari (Wave of Beauty). Shri Mataji has commented that the diagram also represents the chakra system seen looking down from the sahasrara (Crown Chakra)

The central part of the diagram, is a lot harder to construct than it looks, as the lines must intersect accurately or small superfluous triangles will be created. Additionally, the apexes of the triangles must touch the horizontal lines. 

Here's a link to some interesting research on Shri Chakra: sriyantraresearch.com