Sacred geometry involves sacred universal patterns used in the design of everything in our reality, most often seen in sacred architecture and sacred art. The basic belief is that geometry and mathematical ratios, harmonics and proportion are also found in music, light, cosmology. This value system is seen as widespread even in prehistory, a cultural universal of the human condition.
The architecture of GOD. The universe is created by a consciousness which manifests in physical reality through a blueprint that we call Sacred Geometry which repeats over and over giving the illusion of linear time. -Thoth
Learning about India: The Lotus Temple and Sacred Geometry
Throughout history, sacred geometry has been expressed in music, architecture, meditation, painting, and observed in the natural world. Once you become aware of them, the principles of sacred geometry can be seen and used in a vast number of ways. Today it can be applied to the digital space through concepts of elegant design in programming, magical experience design in the event space, and web architecture designed to mirror natural ratios
Floor plan using Phi & Fibonacci by EarthLogeDesigns, "The golden section is used [to] create proportion and scale. Fractals are used extensively for layout and dimensioning. The resultant sacred geometry has self similarity which is found everywhere in nature."