Quadratura is the painting of architecture that does not exist. On a flat ceiling or a curved vault, the painter adds columns, arches, cornices and balconies drawn in perspective, so that they seem to carry the real walls of the room upward.
Seen from the floor, the room appears to have no roof. The painted building keeps rising until it opens onto the sky.
The name is Italian, from the Latin quadratura, "squaring," and it suits a craft built on geometry. Before touching a brush, a painter of quadratura worked from plans, measured lines and vanishing points, the tools of an architect. In Italy in the seventeenth century, the specialists who did this work were called quadraturisti.
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The most famous example covers the vault of Sant'Ignazio, a Jesuit church in the center of Rome. Andrea Pozzo painted it between 1691 and 1694. He was a Jesuit lay brother, a member of the order who was not a priest.
His ceiling sits above the nave, the long central hall of the church. The real walls stop at the cornice, the molded ledge that runs along their top.
Above that line, everything is paint. Tall columns and arches carry the church up into the open air, and in the middle of the sky Saint Ignatius of Loyola, the founder of the Jesuits, rises toward heaven.
The illusion has one condition: it works from a single place. A disc set into the marble floor of the nave marks the spot where the painted architecture lines up exactly with the real one. A few steps away, the spell breaks and the columns start to lean, as if the building were tipping over.
The trick itself was much older than Pozzo. Painters had been opening ceilings onto the sky for more than two centuries by then, and the most famous early case is in Mantua, in northern Italy, in the fifteenth century.
Mantegna's painted oculus
In the Ducal Palace of the Gonzaga, the family that ruled Mantua, a small room is known as the Camera degli Sposi, the "bridal chamber…"
What You'll Discover
Why a ceiling often needed two painters.
How a candle helped Pozzo paint a curved vault.
The dome that exists only in paint.
What Pozzo admitted about his own illusion.
How one book carried the method across Europe.