Give the flight of steps before a temple an odd number, so that one who starts with the right foot will also set the right foot first on the top.
Rules · Plans · Domes · Theory
The centrally planned church
Where the purpose allows, plan the church about a single centre (a circle, a square or a Greek cross) so that every part stands in the same relation to the middle, under a dome.
Alberti recommends round, square and polygonal plans for temples, drawing on nature, which delights in the circle, and on ancient buildings such as the Pantheon. For the next century the central plan was the ideal of architects even when the liturgy, which needed a long nave for processions and preaching, pulled the other way. Bramante’s plan for new St Peter’s (1506) was a Greek cross under a great dome; the church as built was lengthened into a Latin cross by Carlo Maderno in 1607–14.
The central plan survived most successfully in chapels, martyria and pilgrimage churches such as Santa Maria della Consolazione at Todi (begun 1508), and it returned in the oval plans of the Baroque, which combine a centre with a direction (The oval plan).
Related rules
To set a round dome on a square bay, imagine a sphere passing through the four corners of the square; cut it by the four vertical planes of the sides and by the horizontal plane of their crowns. The four spherical triangles left in the corners are the pendentives; the circle at their top carries the dome.
sphere radius R = S⁄√2; arches = sphere ∩ side planes (radius S⁄2); ring at h₀ + S⁄2 with radius S⁄2
If the sphere that forms the pendentives is simply continued above the ring, the bay is covered by a single shallow dome, the sail vault or pendentive dome, which springs directly from the four corners.
crown = h₀ + S⁄√2 (lower than a hemisphere on the ring, h₀ + S)
Lift the dome on a cylindrical or polygonal drum pierced with windows between the ring of the pendentives and the springing of the dome, to light the centre of the church and to make the dome visible from afar.
drum height ≈ ⅓–1 × its radius (Byzantine); much taller in Russian churches
Give the villa garden porticoes for sun and for shade, grottoes made in imitation of nature with tufa and shells, evergreens planted in straight rows at equal distances, and hedges of box; set vines on columns over the walks.
Lay the ideal garden out on a circular plan in concentric rings, woods outside, then meadows and orchards, then gardens of knots and clipped evergreens divided by walks, with water and the fountain of the goddess at the centre.
Cite this page Chris Paton, “The centrally planned church”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/centralized-plan. Text, drawings and models licensed under CC BY-NC 4.0.