Ground plan of the Chigi Chapel

This technical drawing shows a centralized floor plan based on a square with chamfered corners, creating an octagonal interior space. Shaded areas indicate the thickness of the masonry and the placement of four corner niches, while a grid system underlies the entire composition. Handwritten measurements in 'palmi' are noted across the plan to specify the chapel's proportions.

The Chigi Chapel represents a synthesis of High Renaissance architecture and Neoplatonic cosmology, designed to symbolize the soul's ascent through the planetary spheres. Raphael’s use of centralized, geometric harmony reflects the philosophical belief that terrestrial architecture should mirror the mathematical perfection of the divine cosmos.