Why go
This short architectural reading changes what you see before entering the Duomo. Giovanni Pisano's lower façade concentrates sculpture around three portals, while later work rises toward the rose window and pinnacles. The shift in styles and the slightly offset upper elements reveal a building adjusted over generations, rather than a façade executed from one fixed plan.
The full story
Stand back far enough to take in the whole west front of Siena Cathedral, then move closer to the three portals. The lower zone was developed under Giovanni Pisano from the late thirteenth century, using coloured marble and dense carving around the entrances. It has a horizontal rhythm that keeps the portals together. Above it, the façade rises into a more elaborate Gothic composition. The cathedral's nave was raised during construction, and later designers adapted the upper front to the changed scale. That helps explain why the pinnacles do not line up exactly with the columns below. The rose window and vertical decoration draw the eye upward, while the lower sculpture still invites close inspection at street level. This is a useful place to notice how a medieval project changed hands and ambitions over time. Instead of looking for perfect symmetry, compare the two levels and imagine the practical challenge of completing a monumental front around a building that was still evolving.