Milan Cathedral.

Drawn in pencil this is a copy of the original design of Caesar Caesariano (1521), based upon a series of evenly spaced concentric circles and a modulus of 12 and 7 units, the zodiac and the 7 (known) planets.

I used the modulus to recreate the illustration which I found in a book about geometry by Stephen Skinner.

'Milan Cathedral: The long drawn-out construction of the cathedral saw many changes and many new plans. During the rulership of the Duke Francesco Sforza several artists worked on the building, and both Leonardo da Vinci and Bramante were kept busy working out the proportions of the dome.'