The sacred proportion in architecture, sacred geometry, the golden mean; a list of websites
“Divine Proportione” by Luca Pachioli
Geometry in Art and Architecture
The Golden Section, Fibonacci Numbers.
ISAMA
The International Society of the Arts, Mathematics, and Architecture
Mathematics and art, Wikipedia entry.
Mathematics and Architecture
Helmer Aslaksen, Department of Mathematics, National University of Singapore
Nexus Journal
Nexus Network Journal is a peer-reviewed resource resource for studies in architecture and mathematics.
Palladio Museum. Il Centro Internazionale di Studi di Architettura Andrea Palladio
Sacred Geometry in Ancient Egypt
Sacred geometry in architecture.
Wikipedia entry on sacred geometry.