To combine the unity of a central plan with the direction a church needs, plan the space as an oval, set across the axis to widen the view of the altar, or along it to lead the eye towards it.
Rules · Cities · Plans · Optics
Straight streets between the great churches
Join the principal churches of the city by straight streets cut across hills and empty land, so that a pilgrim can walk from one to the next directly, and mark the end of every street with an obelisk visible from far away.
Sixtus V reigned for only five years (1585–90), but with Domenico Fontana he gave Rome the pattern it still has. The Strada Felice ran straight from Trinità dei Monti over the Viminal and Esquiline to Santa Maria Maggiore, and was continued toward Santa Croce in Gerusalemme; other streets joined Santa Maria Maggiore to the Lateran and to the city gates. Ancient obelisks, found fallen or half-buried, were raised at St Peter’s (1586), Santa Maria Maggiore (1587), the Lateran (1588) and Piazza del Popolo (1589), each at the end of a long street.
The obelisk gave the new streets a goal and a point to aim at, and it was a sign of Christian triumph, crowned with a cross. The idea of closing a straight vista on a vertical monument became a basic device of Baroque town planning, from Rome to Versailles, St Petersburg and Washington.
Related rules
Divide the inside of a dome into coffers that shrink in step with the meridians as they rise, so that their perspective deepens the dome and draws the eye to the light of the lantern.
Let the wall of a façade curve in plan (concave, convex, concave) so that the front answers the street, the light and the space within, and the order bends with it.
Make the stair of a palace a processional space: one broad flight rising to a landing, then turning back in two flights either side to arrive at the principal floor beneath a single great vault.
Make the parterre oblong rather than square, since figures somewhat oblong look better on the ground than square ones; later practice made it as broad as the front of the house and about twice as long.
parterre oblong; later practice: width ≈ house front, length ≈ 2 × width
Proportion the width of an allée to its length: a walk of about 100 toises (some 200 m) should be 5 or 6 toises wide, one of 200 toises 7 or 8, and so on, so that a long walk does not seem to narrow to a slot in the distance.
100 toises long → 5–6 wide · 200 → 7–8 · 300 → 9–10 · 400 → 10–12 (1 toise ≈ 1.95 m)
Cite this page Chris Paton, “Straight streets between the great churches”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/sixtine-streets. Text, drawings and models licensed under CC BY-NC 4.0.