Architectural Design and Medieval Geometry at the 13th Century St. Francis Basilica at Assisi (I)

André Frans De Naeyer

University College Antwerpen, Belgium

Abstract: By measuring all architectural dimensions of the present S. Francis Basilica, and converting the results into the 13^th century. foot-standard, the author discovered a simple but coherent design technique based on a biblical 40 feet modulus (= 11.84 m) and the geometry of the square, the circle and the triangle. All anomalies revealed indication for the chronology of the project, and the full metric analysis demonstrated a large vocabulary of clerical and secular semantics included within the medieval arithmetic and design.